Keto, carnivore, and fad diets: a calm reality check

If you’ve tried keto, carnivore, or the latest plan everyone swears by and ended up more confused than when you started, that’s a common place to land, and you don’t owe anyone an apology for it.

Every year brings a new diet with a confident name: keto, carnivore, paleo, “clean,” and whatever is trending this month. Some contain good ideas; most overpromise. This guide helps you judge a diet calmly, without shame for having tried one.

The best eating pattern is one that fits the evidence and your life—and that you can keep doing.

How popular diets compare

In 2023, an American Heart Association scientific statement scored popular eating patterns against the AHA’s heart-health guidance. DASH, Mediterranean-style, pescatarian, and vegetarian patterns aligned best. Vegan and low-fat patterns came next. Very-low-fat and low-carbohydrate patterns aligned less well, and paleo and very-low-carbohydrate/ketogenic patterns aligned least—largely because they restrict fruits, whole grains, and legumes.

What about lower-carb eating?

Lower-carb is not the same as keto. The 2025–2030 Dietary Guidelines note that some people with certain chronic diseases may do better with a lower-carbohydrate diet and advise working with a health care professional to find what fits. The ADA Standards of Care likewise say reducing overall carbohydrate intake can help some people with diabetes, among several eating patterns. Moderate carbohydrate reduction built on vegetables, proteins, nuts, and legumes is very different from eliminating fruit, beans, and whole grains.

Carnivore and other single-food-group diets

Eating only animal foods removes every food group that supplies fiber and many vitamins, and it often means high saturated fat. The Academy of Nutrition and Dietetics advises avoiding any diet that eliminates or severely restricts entire food groups or macronutrients. Its long-term safety and benefits have not been established in high-quality studies.

Fad-diet red flags

The Academy’s guidance is simple: if a diet or product sounds too good to be true, it probably is. Watch for:

• Promises of rapid weight loss. Losing weight quickly can mean losing more muscle, regaining the weight, and risking hair loss, dehydration, and gallstones.
• Eliminating whole food groups or macronutrients.
• Special food combinations or timing rules—there is no evidence these help with weight loss.
• Rigid meal plans that ignore your culture, budget, and schedule.
• Products to buy as the centerpiece of the plan, or “detox” claims (see detox and cleanse myths).

Safety cautions

• Diabetes medicines: cutting carbohydrates sharply while taking insulin or certain other diabetes medicines can cause low blood sugar, and some medicines carry other risks on very-low-carb diets. Talk with your prescriber before starting.
• Pregnancy, breastfeeding, kidney disease, and a history of eating disorders are reasons not to start a restrictive diet without your care team.
• Children and teens should not follow restrictive diets unless a clinician prescribes one.

What tends to work instead

Regular meals built from vegetables, fruit, whole grains, protein foods, and dairy or fortified alternatives; fewer highly processed foods and sugary drinks; movement you enjoy; sleep; and support. It is less exciting than a new diet—and more likely to last. The Anchor Plan turns that into a weekly structure.

When to see a clinician or registered dietitian

Talk to a clinician before starting a restrictive diet if you take medicines for diabetes or blood pressure, have kidney, liver, or heart disease, or are pregnant. If you find yourself cycling through diets, feeling guilt or fear around food, or bingeing after restriction, a registered dietitian or mental health professional experienced in eating disorders can help.

A short “good enough” check

• The plan I’m considering keeps most food groups.
• It doesn’t promise rapid weight loss or sell me supplements.
• I’ve checked with my clinician if I take medicines or have a chronic condition.
• I could see myself eating this way a year from now.

Sources

• Gardner CD, et al. Popular Dietary Patterns: Alignment With American Heart Association 2021 Dietary Guidance: A Scientific Statement From the American Heart Association. Circulation. 2023. https://www.ahajournals.org/doi/10.1161/CIR.0000000000001146
• Academy of Nutrition and Dietetics (eatright.org). Staying Away from Fad Diets. https://www.eatright.org/health/wellness/diet-trends/staying-away-from-fad-diets
• U.S. Department of Agriculture & U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2025–2030 (January 2026). https://cdn.realfood.gov/DGA.pdf
• American Diabetes Association Professional Practice Committee. 5. Facilitating Positive Health Behaviors and Well-being to Improve Health Outcomes: Standards of Care in Diabetes—2026. Diabetes Care 2026;49(Suppl 1). https://diabetesjournals.org/care/article/49/Supplement_1/S89/163932/5-Facilitating-Positive-Health-Behaviors-and-Well