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Clean Keto: The Whole-Food Ketogenic Lifestyle

A very-low-carb, high-fat, moderate-protein way of eating built on grass-fed meats, pastured eggs, wild fatty fish, leafy greens and quality fats such as olive oil and avocado. The clean version emphasizes real food and nutrient density, distinguishing it sharply from "dirty keto," which leans on processed meats, artificial sweeteners, and deep-fried and ultra-processed foods.

🥩 Grass-Fed & Pastured 🥬 Vegetables at Every Meal 🥑 Olive Oil & Avocado First ⏱️ Intermittent Fasting Friendly ⚡ Electrolyte-Aware

Last updated:

By the Numbers, United States

How Many Americans Follow This Lifestyle?

4%
of US adults said they had followed a ketogenic or high-fat diet in the past year (online survey of 1,022 adults, April 2023)1

Source: IFIC Food & Health Survey, 2023. Self-reported; figures vary widely across surveys.

Definition

What Is Clean Keto?

Keto is a very-low-carb eating pattern (typically 20 to 50 g of net carbs per day) that shifts the body's primary fuel from glucose to fat-derived ketones2. The "clean" version means whole, traditional, nutrient-dense foods only, no deep-fried or ultra-processed foods, no fake sweeteners, no protein bars and a strong emphasis on vegetables.

The ketogenic diet was first described at the Mayo Clinic in 1921 as a treatment for epilepsy, and it is still used today, mainly for children whose seizures continue despite medicines34. It later became popular through low-carbohydrate diet books, and clinical research on nutritional ketosis has continued since. The whole-food version of it, built on pasture-raised animal foods and abundant vegetables, is the one described here.

The core insight is metabolic: when carbohydrate is restricted enough that the liver runs low on glycogen, it begins producing ketone bodies (β-hydroxybutyrate, acetoacetate, acetone) from fatty acids. These ketones can fuel the brain, heart and muscles, and in laboratory studies they also act as signaling molecules, though what that means for health in people is not yet established5.

Whole-food keto bowl with grass-fed meat, leafy greens, avocado and watermelon radish

Clean Keto vs. Standard Keto vs. Dirty Keto

Clean Keto (Healthy)

Pastured eggs, grass-fed meats, wild fatty fish, organ meats, leafy greens, cruciferous, avocado, olive oil, ghee, coconut oil, nuts. Vegetables at every meal. Strong nutrient density.

Standard Keto

Macros are correct but quality is ignored. Conventional meat, dairy, butter, cheese. Vegetable intake is often minimal. Can work for weight loss, but with few vegetables it is hard to get enough fiber, potassium, magnesium and folate.

Dirty Keto

Processed bacon, hot dogs, "keto" snack bars, artificial sweeteners, deep-fried foods. Hits the macros but is low in nutrients, and it leans on processed meat, which the WHO classifies as a cause of cancer6.

The Framework

Six Core Principles

🌾

1. Real Food Only

If your great-grandmother wouldn't recognize it as food, it doesn't belong on the plate. No "keto" bars, no diet sodas, no seed-oil snacks. A "keto" label on a wrapper usually means the product is processed.

🫒

2. Quality of Fat Matters

Make extra-virgin olive oil, avocado and avocado oil, nuts and fatty fish your main fats, and keep grass-fed butter, ghee, tallow, lard from pastured pork, coconut oil and MCT oil to small amounts. Keep deep-fried and packaged foods low; the claim that seed oils such as soybean or canola are uniquely harmful is not supported by controlled trials7. For heart health, the strongest evidence favors olive oil, avocado, nuts and fatty fish over butter, tallow, lard and coconut oil, because swapping saturated fat for unsaturated fat lowers LDL cholesterol and heart disease risk7.

🥬

3. Vegetables Come First

The defining feature of a clean version: vegetables at every meal, primarily leafy greens and cruciferous vegetables. This is where the potassium, magnesium, vitamin C, vitamin K1, folate and fiber come from. Skipping vegetables makes it hard to get enough of these nutrients.

🐟

4. Pastured / Wild Protein

Grass-fed beef, pastured eggs, pastured pork, wild-caught fatty fish (sardines, anchovies, wild salmon). Don't fear protein, but don't overshoot it: about 0.7 to 1.0 g per pound of lean body mass (1.5 to 2.2 g per kg), meaning your weight without body fat, is the typical range.

⚡

5. Electrolyte Awareness

In the first days of very-low-carb eating, the body sheds extra water and salt2. Some people report a short spell of "keto flu" in the first weeks, most often headache, fatigue, nausea and dizziness8. Extra salt and fluid are commonly suggested. A common practitioner target, not one drawn from trials, is ~5 g sodium, 4 to 5 g potassium, 400 to 600 mg magnesium daily, especially in the first weeks. For comparison, the Dietary Guidelines advise most adults to keep sodium under 2,300 mg a day, so treat the higher figure as a short-term measure for the first weeks, and only if your clinician agrees9. The sodium figure is not for anyone told to limit salt, which includes many people with high blood pressure, heart failure or kidney disease; ask your own clinician first. Potassium at this level is not safe for everyone. If you take an ACE inhibitor, an ARB, a potassium-sparing diuretic such as spironolactone, or regular anti-inflammatory painkillers such as ibuprofen, or if you have reduced kidney function, this much potassium can raise blood potassium to a dangerous level10. Check with your prescriber before aiming at these figures. This whole range is above the 350 mg/day upper intake level for supplemental magnesium; above that, diarrhea is common. With kidney disease, take it only on your clinician's advice.

⏱️

6. Intermittent Fasting Integration

Clean keto pairs naturally with time-restricted eating (often 16:8 or one-meal-a-day). Some people find the two combine easily. Claims that fasting adds autophagy or cognitive benefits in people are not established; see the intermittent fasting guide.

Food Framework

What to Eat & What to Skip

✅ Build Meals Around:

🥩 Pastured Animal Foods

Grass-fed/finished beef, pastured eggs (2 to 6/day; for comparison, the American Heart Association suggests up to 1 a day for most healthy people and up to 2 for older adults with normal cholesterol, so if your LDL cholesterol is high or you have diabetes, ask your clinician11), pastured pork, lamb, bison, wild salmon, sardines, anchovies, Atlantic mackerel, oysters. Organ meats 1 to 2x/week. A 3-⁠ounce serving of beef liver has more than twice the 3,000 mcg of vitamin A that pregnant women are advised not to exceed, so anyone who is or may become pregnant should avoid liver12.

🥬 Above-Ground Vegetables

Spinach, kale, romaine, arugula, broccoli, cauliflower, cabbage, Brussels sprouts, zucchini, asparagus, peppers, celery, cucumber, mushrooms. Some root vegetables in moderation (radishes, turnips).

🥑 Quality Fats

Mainly extra-virgin olive oil, avocado oil, avocados, olives, nuts (macadamia, pecan, walnut, Brazil) and seeds (chia, flax, pumpkin). Coconut oil, MCT oil, grass-fed butter, ghee, tallow, duck fat and pastured lard in small amounts.

🧂 Fermented & Functional

Sauerkraut, kimchi, fermented pickles, plain coconut yogurt or grass-fed kefir, bone broth, raw apple cider vinegar.

🍓 Small Amounts of Low-Carb Fruit

Berries (raspberries, blackberries, strawberries, blueberries, moderate), lemons, limes. Saved for after fat-adaptation; usually 1/4 to 1/2 cup as needed.

❌ Eliminate or Strictly Limit:

🍟 Deep-Fried & Ultra-Processed Foods

Fried restaurant food, chips and packaged snacks. Cook with olive oil at home instead.

🍬 Refined Sugar & Sweeteners

Sugar, high-fructose corn syrup, agave, honey (mostly), maple syrup. Also: aspartame, sucralose, acesulfame-K. In a two-week trial, sucralose, saccharin, aspartame and stevia each changed the gut microbiome, and sucralose and saccharin worsened blood sugar responses in some people13. If you use a sweetener, keep it small and occasional; monk fruit and allulose are common choices.

🌾 Grains

Wheat, oats, rice, corn, quinoa and all flours made from them. Also: bread, pasta, pastries, cereal, granola, "keto" bread products that use processed wheat protein isolates.

🫘 Most Legumes

Beans, lentils, chickpeas: carb content is too high for ketosis in usual portions14. Peanuts are a legume but are about as low in carbohydrate as walnuts, so small amounts can fit14.

📦 "Keto-Labeled" Processed Foods

Bars, cookies, ice cream, chips, cereals, breads marketed as keto. Many contain wheat protein isolates, gums, sweeteners and added fats. The label is a warning sign, not a green light.

🥛 Conventional Dairy

Skip or strongly limit milk and cheese. If using dairy: grass-fed butter, ghee, aged cheese and fermented dairy (kefir, full-fat yogurt), from pastured animals if you prefer.

A Day on the Plate

Sample 1-⁠Day Clean Keto Pattern

A typical 16:8 day. Adapt timing, portions and macros to your individual context.

7:00 to 11:00 AM · Fasted Window
🌅 Morning, Just Water, Electrolytes, Coffee

No food. Drink water with a pinch of pink salt, lemon juice and (optional) a quality electrolyte mix. One cup of black coffee, espresso or tea is fine: no sweeteners, no creamers, no MCT-oil or butter coffee (these add calories, which breaks the fast).

Morning keto ritual: a glass of warm water with lemon, a small dish of pink salt and a cup of black coffee

Morning Ritual

16 oz (475 mL) water with a pinch of pink Himalayan salt + 1/2 lemon's juice · 1 cup of black coffee · optional electrolyte packet (sodium + potassium + magnesium). No food, no sweeteners, no creamers. This is the simplest possible practice and the foundation of the day.

11:00 AM to 12:00 PM · Meal 1 (Breakfast)
🥑 Late-Morning Plate

3 pastured eggs scrambled in 1 tbsp ghee · 2 cups sautéed spinach in olive oil with garlic · 1/2 avocado · 4 oz (115 g) wild salmon · large mug of plain bone broth. If hungrier, add another egg or extra greens. Net carbs land around 5 to 8 g14.

Keto breakfast plate with pastured eggs, sautéed spinach, avocado and wild salmon

🥑 Sample Breakfast, Meal 1

Eggs · greens · avocado · wild salmon · bone broth. All real-food fats and proteins. Bone broth adds collagen, glycine and electrolytes; the greens cover potassium, magnesium, folate and vitamin K.

5:30 to 6:30 PM · Meal 2 (Dinner)
🥩 Evening Plate

6 to 8 oz (170 to 225 g) grass-fed ribeye or wild salmon · 3 cups mixed leafy greens with extra-virgin olive oil + lemon · 1 cup roasted Brussels sprouts or broccoli in olive oil · small side of fermented sauerkraut · sparkling water with lime. Optionally: 1/4 cup berries with a tablespoon of full-fat coconut yogurt for dessert.

Keto early dinner with grass-fed steak, leafy greens, roasted Brussels sprouts and sauerkraut

🥩 Sample Early Dinner, Meal 2

Grass-fed steak (or wild salmon) · big leafy salad with olive oil + lemon · roasted cruciferous in olive oil · fermented sauerkraut. Finishing dinner by 6:30 PM gives you about 16 hours without food before Meal 1 the next day.

8:00 to 11:00 PM · Fasting Window
🌙 No Food, Electrolyte Sip Before Bed

Finishing your last meal a few hours before bed fits the fasting window. A glass of water with sea salt + magnesium glycinate is a common bedtime habit, often taken for night cramps, though trials have not found that magnesium prevents cramps in older adults15.

Practical Guardrails

The Six Most Common Pitfalls

⚡ Not Replacing Electrolytes

Low salt and fluid intake may add to "keto flu" symptoms. A common practitioner target, not one drawn from trials, is 5 g sodium, 4 to 5 g potassium, 400 to 600 mg magnesium per day, especially in weeks 1 to 4 and around exercise. For comparison, the Dietary Guidelines advise most adults to keep sodium under 2,300 mg a day, so treat the higher figure as a short-term measure for the first weeks, and only if your clinician agrees9. The sodium figure is not for anyone told to limit salt, which includes many people with high blood pressure, heart failure or kidney disease; ask your own clinician first. Potassium at this level is not safe for everyone. If you take an ACE inhibitor, an ARB, a potassium-sparing diuretic such as spironolactone, or regular anti-inflammatory painkillers such as ibuprofen, or if you have reduced kidney function, this much potassium can raise blood potassium to a dangerous level10. Check with your prescriber before aiming at these figures. This whole range is above the 350 mg/day upper intake level for supplemental magnesium16; above that, diarrhea is common. With kidney disease, take it only on your clinician's advice.

🥬 Skipping Vegetables

Going to bacon-and-cheese keto is the classic trap. Without abundant leafy greens and cruciferous vegetables, you can easily fall short on potassium, magnesium, folate, vitamin C and fiber. Aim for vegetables at every meal.

🍬 Artificial Sweeteners

Aspartame, sucralose, acesulfame-K. In small trials, sucralose changed the gut microbiome and raised the insulin response to a glucose drink in some people1317. Use a sweetener sparingly if at all. If you use one, keep it to small amounts of monk fruit or allulose.

🥓 Processed Meats

Conventional bacon, hot dogs, deli meats with nitrites and preservatives. Pastured and "nitrate-free" versions are still processed meat, so keep all of them occasional add-ons rather than dietary staples6.

🥛 Cheese as a Crutch

Easy, dense, satisfying and easy to overeat. Some people stall when they eat a lot of dairy. If progress stops, try cutting back on dairy for two weeks and see what changes.

📈 Protein Without Balance

The body can make glucose from protein (gluconeogenesis), but a study in healthy adults found that protein from a meal added little to the glucose the body made18, so the point is balance rather than fear of protein: aim for moderate protein (about 0.7 to 1.0 g per pound of lean body mass, or 1.5 to 2.2 g per kg) and let fat fill the remaining caloric need.

Foundational Supplements

Supplements Often Helpful on Clean Keto

Not a substitute for food. Some people find a few of these helpful; none is required.

SupplementWhyTypical DoseNotes
Electrolytes (Na + K + Mg)Replaces sodium and fluid lost in the first weeks2; may ease "keto flu" symptoms5 g sodium · 4 to 5 g potassium, mostly from food (leafy greens, avocado), not pills10 · 400 to 600 mg magnesium per dayPink salt and magnesium glycinate; get potassium from leafy greens and avocado, not from cream of tartar or potassium powders. Skip the extra sodium if you have been told to limit salt, as many people with high blood pressure, heart failure or kidney disease have. For comparison, the Dietary Guidelines advise most adults to keep sodium under 2,300 mg a day, so treat the higher figure as a short-term measure for the first weeks, and only if your clinician agrees9. Potassium at this level is not safe for everyone. If you take an ACE inhibitor, an ARB, a potassium-sparing diuretic such as spironolactone, or regular anti-inflammatory painkillers such as ibuprofen, or if you have reduced kidney function, this much potassium can raise blood potassium to a dangerous level10. Check with your prescriber before aiming at these figures. This whole range is above the 350 mg/day upper intake level for supplemental magnesium16; above that, diarrhea is common. With kidney disease, take it only on your clinician's advice.
Vitamin D3 + K2Most Americans get less vitamin D from food than recommended, and low blood levels are more likely with little sun, darker skin, older age or obesity19; K2 is involved in how the body uses calcium, though supplement benefits for bone and arteries are not established2021D3: Set the dose with your clinician; most adults need no blood test first · K2 MK-⁠7: 200 mcgTest 25-⁠OH-D only when your clinician advises it, not as a routine. If you take warfarin, clear any vitamin K supplement with the clinician managing your anticoagulation before starting or stopping it: vitamin K antagonizes warfarin, and changing your intake destabilizes the INR. Consistency matters more than avoidance21. This does not apply in the same way to direct oral anticoagulants such as apixaban or rivaroxaban, but tell your prescriber about any supplement you take22.
Omega-⁠3 Fish OilA source of EPA and DHA if you eat little fatty fish; the ideal omega-⁠6 to omega-⁠3 ratio, if there is one, has not been defined232 to 3 g EPA+DHA per day23Use a third-party-tested, low-oxidation product. In trials, supplements above 1 g a day were linked to a higher risk of atrial fibrillation, so agree on this dose with your clinician24. Wild fatty fish 3+ times/week reduces the need.
B-ComplexGrains are a main source of thiamin (B1) in the US diet, and enriched grains carry added folic acid, so cutting them can lower both25261 capsule daily with breakfastStandard or methylated forms both work; people with an MTHFR variant can process ordinary folic acid27.
Digestive Enzymes (lipase-forward)Some people without a gallbladder use these with fatty meals; evidence is limited1 to 2 capsules with each large mealOx bile with lipase is sometimes used after gallbladder removal, when bile is no longer stored and released in response to a fatty meal.
MCT Oil (C8/C10)Quick-converting medium-chain fats; supports ketogenesis281 to 2 tablespoons/day, build up slowlyStart with 1 tsp; larger amounts can cause stomach upset4. Take it with food or in coffee within the eating window.
Iodine + SeleniumDairy and grains are major US sources of iodine, so cutting them and using non-iodized salt such as pink salt can lower iodine intake29Iodine: 150 to 300 mcg · Selenium: 200 mcg from a supplement, or 1 to 2 Brazil nuts instead (amounts vary widely)Both are needed for normal thyroid function. Brazil nuts vary widely: one nut can hold more than 100 mcg of selenium, or 10 times less, depending on the soil30. Selenium has an upper limit of 400 mcg a day from food and supplements together, so do not add Brazil nuts on top of a supplement31. Skip selenium supplements if you have type 2 diabetes or are at risk of it30. If you have a thyroid condition, ask your clinician before taking iodine29.
Magnesium GlycinateSome people choose the glycinate form because they find it easier on the gut300 to 500 mg elemental, at bedtime (or split AM/PM)This is the same magnesium as the Electrolytes row, not an addition to it. Count the two magnesium forms together against the upper intake level given below. Some people find it helps with sleep. It is often taken for night cramps, though trials have not found that magnesium prevents cramps in older adults15, and palpitations need a clinician's assessment rather than a supplement. Skip oxide and citrate if loose stools are an issue. The top of this range is above the 350 mg/day upper intake level for supplemental magnesium; above that, diarrhea is common. With kidney disease, take it only on your clinician's advice.
Zinc CarnosineA zinc and carnosine compound; there is no evidence that a higher-fat diet calls for it, so treat it as optional75 to 150 mg/day (delivers about 17 to 34 mg elemental zinc)Take with food. Zinc from supplements and food together should stay under the 40 mg/day upper limit, and oysters and red meat are rich in zinc32. After 8 to 12 weeks, drop to the lower dose to avoid copper depletion. Long-term high zinc can cause copper deficiency33, so pair with 2 mg copper if used long term34.
Suitability

Who Benefits Most, and Who Should Be Careful

💪 Often Benefits

Insulin resistance & metabolic syndrome

In trials in type 2 diabetes, low-carb diets improved weight, triglycerides and insulin sensitivity at six months, though the gains shrank by 12 months35.

Type 2 diabetes

Trial evidence for clinical remission35, though the longest-running data come from a commercial program with a financial interest in the result36. Medications must be adjusted by a physician2, and anyone taking an SGLT2 inhibitor should not start a ketogenic diet without their prescriber's agreement, because the combination can cause ketoacidosis with normal blood sugar37.

Drug-resistant epilepsy

The original medical use. Specialists recommend considering it for children whose seizures continue after two medicines4; evidence in adults is less certain38.

Neurodegeneration (research)

Being studied in Alzheimer's and Parkinson's disease; no benefit is established yet.

Fatty liver (NAFLD)

Liver fat falls substantially, though the effect tracks weight loss more than ketosis itself, and comparable results follow other diets at similar weight loss3940.

⚠️ Use Caution or Avoid

Type 1 diabetes

Only under close endocrinology supervision; ketoacidosis risk if insulin management is imperfect2.

Pregnancy & breastfeeding

Not the right time to sharply restrict carbohydrates; nutritional needs are different2.

Eating disorder, current or past

Restrictive frameworks can re-trigger disordered patterns2. Work with a clinician.

Kidney disease

Ask your kidney doctor first; very-low-carb eating has not been studied enough in kidney disease, and the electrolyte and magnesium advice on this page may not be safe for you2.

Thyroid conditions

In a small three-week trial in healthy adults, T3 fell on a ketogenic diet41. What this means for people with thyroid conditions is not known, so check with your clinician and keep your thyroid tests on schedule.

High-volume endurance athletes

Possible but requires careful planning. In elite race walkers, a ketogenic diet raised fat burning but impaired race-pace performance, so athletes who compete at high intensity may do worse on it42.

Gallbladder removed

Some people add ox bile + lipase while adjusting; the evidence for it is limited, and raising fat gradually is the simpler first step.

Next Steps

This Is a Template: Adapt It to Your Body

Clean keto suits some people well and others poorly. Take it as a framework (not a religion) and combine it with the lab work, symptom feedback and clinical guidance specific to you.

← Back to Lifestyle Library Compare to Clean Vegetarian →

References & Evidence Notes

Each numbered entry below is either a source you can follow or a note setting out what the evidence does and does not support. Both are numbered together so the markers in the text line up.

Last reviewed October 20, 2026. This page is nutrition education, not medical advice, and it does not replace your doctor. If you take medicine for diabetes, the doses must be adjusted by your physician, and anyone taking an SGLT2 inhibitor, anyone with type 1 diabetes, kidney disease or a history of an eating disorder, and anyone who is pregnant should agree on any change with their clinician first. The sodium, potassium and magnesium targets on this page are not safe for everyone.

  1. International Food Information Council. 2023 Food & Health Survey. 2023. ific.org. An online survey of 1,022 US adults aged 18 to 80, asked which eating patterns or diets they had followed at any time in the past year. 4% chose "ketogenic or high-fat"; the answers are self-reported. ↩
  2. Evert AB, et al. Nutrition Therapy for Adults With Diabetes or Prediabetes: A Consensus Report. Diabetes Care. 2019. PubMed 31000505. The American Diabetes Association's consensus report for adults with diabetes or prediabetes. It supports the 20 to 50 g carbohydrate range, the early loss of water, the need to reduce diabetes medicines, the lack of trials in type 1 diabetes and the concerns about very-low-carb eating in kidney disease, disordered eating and pregnancy. ↩
  3. Höhn S, et al. History of dietary treatment from Wilder's hypothesis to the first open studies in the 1920s. Epilepsy Behav. 2019. PubMed 31677579. A history of the diet's origins: Wilder, at the Mayo Clinic, published on ketosis and epilepsy in 1921. ↩
  4. Kossoff EH, et al. Optimal clinical management of children receiving dietary therapies for epilepsy: Updated recommendations of the International Ketogenic Diet Study Group. Epilepsia Open. 2018. PubMed 29881797. Expert recommendations for children on dietary therapy for epilepsy: the diet should be strongly considered once two seizure medicines have failed. It also notes stomach upset with MCT oil, though in children on high-MCT epilepsy diets rather than adults. ↩
  5. Puchalska P, Crawford PA. Multi-dimensional Roles of Ketone Bodies in Fuel Metabolism, Signaling, and Therapeutics. Cell Metab. 2017. PubMed 28178565. A review of how ketones fuel the brain, heart and muscle and act as signaling molecules. ↩
  6. World Health Organization. Carcinogenicity of red and processed meat (Questions and answers). who.int. Processed meat is classified as Group 1, carcinogenic to humans. ↩
  7. Sacks FM, et al. Dietary Fats and Cardiovascular Disease: A Presidential Advisory From the American Heart Association. Circulation. 2017. PubMed 28620111. The American Heart Association's review of trials and cohort studies: replacing saturated fat with unsaturated fats, especially polyunsaturated fats, lowers the rate of cardiovascular disease. ↩
  8. Bostock ECS, et al. Consumer Reports of "Keto Flu" Associated With the Ketogenic Diet. Front Nutr. 2020. PubMed 32232045. An analysis of online forum posts by people starting the diet, so weak evidence: the most common symptoms were headache, fatigue, nausea and dizziness, peaking in the first week and fading after four weeks. It does not show that electrolytes prevent them. ↩
  9. US Food and Drug Administration. Sodium in Your Diet. fda.gov. The Dietary Guidelines for Americans advise adults to keep sodium under 2,300 mg a day. ↩
  10. Linus Pauling Institute, Oregon State University. Potassium. lpi.oregonstate.edu. The source for the medicines that can raise blood potassium, including ACE inhibitors, ARBs, potassium-sparing diuretics and anti-inflammatory painkillers, and for the small amounts of potassium in ordinary supplements. ↩
  11. Carson JAS, et al. Dietary Cholesterol and Cardiovascular Risk: A Science Advisory From the American Heart Association. Circulation. 2020. PubMed 31838890. Healthy people can include up to one whole egg a day, and older adults with normal cholesterol up to two. ↩
  12. Office of Dietary Supplements, National Institutes of Health. Vitamin A and Carotenoids: Fact Sheet for Health Professionals. ods.od.nih.gov. Lists 6,582 mcg of vitamin A in 3 ounces of pan-fried beef liver, and the advice that women who are or might be pregnant not take more than 3,000 mcg. ↩
  13. Suez J, et al. Personalized microbiome-driven effects of non-nutritive sweeteners on human glucose tolerance. Cell. 2022. PubMed 35987213. A two-week trial in 120 healthy adults: saccharin, sucralose, aspartame and stevia each changed the gut microbiome, and saccharin and sucralose worsened blood sugar responses. Acesulfame-K was not tested. ↩
  14. US Department of Agriculture. FoodData Central. fdc.nal.usda.gov. Carbohydrate and fiber values for peanuts, walnuts, cooked chickpeas and lentils, spinach, avocado and eggs, used for the net-carb comparisons and the Meal 1 estimate. ↩
  15. Garrison SR, et al. Magnesium for skeletal muscle cramps. Cochrane Database Syst Rev. 2020. PubMed 32956536. A review of trials: magnesium is unlikely to prevent muscle cramps in older adults. It found no trials for exercise cramps. ↩
  16. Office of Dietary Supplements, National Institutes of Health. Magnesium: Fact Sheet for Health Professionals. ods.od.nih.gov. The upper intake level for magnesium from supplements is 350 mg a day for adults. ↩
  17. Pepino MY, et al. Sucralose affects glycemic and hormonal responses to an oral glucose load. Diabetes Care. 2013. PubMed 23633524. In 17 adults with obesity, sucralose taken before a glucose drink raised the insulin response to the drink. ↩
  18. Fromentin C, et al. Dietary proteins contribute little to glucose production, even under optimal gluconeogenic conditions in healthy humans. Diabetes. 2013. PubMed 23274906. A small study of 8 healthy adults given one meal of egg protein: protein from the meal added little to the glucose the body made. ↩
  19. Office of Dietary Supplements, National Institutes of Health. Vitamin D: Fact Sheet for Health Professionals. Updated June 27, 2025. ods.od.nih.gov. Most Americans get less vitamin D from food than recommended, though most have enough in their blood; low levels are more likely with little sun, darker skin, older age or obesity. ↩
  20. Linus Pauling Institute, Oregon State University. Vitamin K. lpi.oregonstate.edu. What vitamin K does in the body, and that no upper limit has been set; it reports that MK-⁠7 taken for three years did not change bone density. ↩
  21. Office of Dietary Supplements, National Institutes of Health. Vitamin K: Fact Sheet for Health Professionals. Updated March 29, 2021. ods.od.nih.gov. Vitamin K's role in how the body uses calcium, and the advice that people taking warfarin and similar blood thinners keep their vitamin K intake consistent. ↩
  22. Kampouraki E, Kamali F. Dietary implications for patients receiving long-term oral anticoagulation therapy for treatment and prevention of thromboembolic disease. Expert Rev Clin Pharmacol. 2017. PubMed 28635328. A review of diet and long-term blood thinners. Whether vitamin K in the diet affects the response to direct oral anticoagulants in people remained to be investigated. ↩
  23. Office of Dietary Supplements, National Institutes of Health. Omega-⁠3 Fatty Acids: Fact Sheet for Health Professionals. Updated August 22, 2025. ods.od.nih.gov. Raising EPA and DHA levels matters more than lowering omega-⁠6 intake, and the FDA has concluded that supplements providing up to 5 g a day of EPA and DHA are safe when used as recommended. ↩
  24. Gencer B, et al. Effect of Long-Term Marine ω-⁠3 Fatty Acids Supplementation on the Risk of Atrial Fibrillation in Randomized Controlled Trials of Cardiovascular Outcomes: A Systematic Review and Meta-Analysis. Circulation. 2021. PubMed 34612056. Pooled heart trials in adults with an average age of 65: atrial fibrillation was more common in the trials that gave more than 1 g a day. ↩
  25. Office of Dietary Supplements, National Institutes of Health. Thiamin: Fact Sheet for Health Professionals. ods.od.nih.gov. Cereals and bread are the most common sources of thiamin in the US diet. ↩
  26. Office of Dietary Supplements, National Institutes of Health. Folate: Fact Sheet for Health Professionals. ods.od.nih.gov. The FDA requires folic acid to be added to enriched breads, cereals and flours. ↩
  27. Centers for Disease Control and Prevention. MTHFR Gene Variant and Folic Acid Facts. cdc.gov. People with an MTHFR gene variant can process all types of folate, including folic acid. ↩
  28. Vandenberghe C, et al. Tricaprylin Alone Increases Plasma Ketone Response More Than Coconut Oil or Other Medium-Chain Triglycerides: An Acute Crossover Study in Healthy Adults. Curr Dev Nutr. 2017. PubMed 29955698. In healthy adults, MCT oil raised blood ketones, and the C8 form raised them most. ↩
  29. Linus Pauling Institute, Oregon State University. Iodine. lpi.oregonstate.edu. Dairy, grains and eggs supply much of the iodine in the US diet, and people with existing thyroid disease may be sensitive to extra iodine. ↩
  30. Linus Pauling Institute, Oregon State University. Selenium. lpi.oregonstate.edu. A Brazil nut can hold more than 100 mcg of selenium or 10 times less, depending on the soil, and people with high selenium status or at risk of type 2 diabetes should avoid selenium supplements. ↩
  31. Office of Dietary Supplements, National Institutes of Health. Selenium: Fact Sheet for Health Professionals. ods.od.nih.gov. The upper intake level for selenium is 400 mcg a day for adults, from food and supplements together. ↩
  32. Office of Dietary Supplements, National Institutes of Health. Zinc: Fact Sheet for Health Professionals. ods.od.nih.gov. The upper intake level for zinc is 40 mg a day for adults, and oysters and red meat are rich sources. ↩
  33. Linus Pauling Institute, Oregon State University. Zinc. lpi.oregonstate.edu. Total zinc of 60 mg a day for up to 10 weeks has caused signs of copper deficiency. ↩
  34. Linus Pauling Institute, Oregon State University. Copper. lpi.oregonstate.edu. The upper intake level for copper is 10 mg a day, well above the 2 mg on this page. ↩
  35. Goldenberg JZ, et al. Efficacy and safety of low and very low carbohydrate diets for type 2 diabetes remission: systematic review and meta-analysis of published and unpublished randomized trial data. BMJ. 2021. PubMed 33441384. Trials in adults with type 2 diabetes: low-carb diets brought remission and improved weight, triglycerides and insulin sensitivity at six months, with the gains shrinking by 12 months. Effects were smaller when remission was defined without medicines. ↩
  36. Athinarayanan SJ, et al. Long-Term Effects of a Novel Continuous Remote Care Intervention Including Nutritional Ketosis for the Management of Type 2 Diabetes: A 2-⁠Year Non-randomized Clinical Trial. Front Endocrinol. 2019. PubMed 31231311. A two-year, open-label, non-randomized study run by a commercial company that sells the program it tested. ↩
  37. Somagutta MKR, et al. Dietary Changes Leading to Euglycemic Diabetic Ketoacidosis in Sodium-Glucose Cotransporter-⁠2 Inhibitor Users: A Challenge for Primary Care Physicians? Korean J Fam Med. 2022. PubMed 36444120. A review of case reports in which people taking an SGLT2 inhibitor developed ketoacidosis with normal blood sugar after changes to their diet. ↩
  38. Martin-McGill KJ, et al. Ketogenic diets for drug-resistant epilepsy. Cochrane Database Syst Rev. 2020. PubMed 32588435. A review of trials in children and adults with drug-resistant epilepsy: the evidence for ketogenic diets in adults remains uncertain. ↩
  39. Ahn J, et al. Critical appraisal for low-carbohydrate diet in nonalcoholic fatty liver disease: Review and meta-analyses. Clin Nutr. 2019. PubMed 30314924. There is little evidence that a low-carb diet helps fatty liver more than a low-calorie diet with the same calories. ↩
  40. Kirk E, et al. Dietary fat and carbohydrates differentially alter insulin sensitivity during caloric restriction. Gastroenterology. 2009. PubMed 19208352. In 22 adults with obesity, liver fat fell faster on a low-carb diet in the first 48 hours, but was similar on both diets once people had lost 7% of their weight. ↩
  41. Iacovides S, et al. Could the ketogenic diet induce a shift in thyroid function and support a metabolic advantage in healthy participants? A pilot randomized-controlled-crossover trial. PLoS One. 2022. PubMed 35658056. A three-week crossover trial in 11 healthy adults: blood T3 was lower after the ketogenic diet. It did not study people with thyroid conditions. ↩
  42. Burke LM, et al. Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers. J Physiol. 2017. PubMed 28012184. In elite race walkers, adapting to a low-carb, high-fat diet impaired performance despite a rise in peak aerobic capacity. ↩