Carnivore diet: how long makes sense?

No study determines how long carnivore makes sense: what is well studied is mostly weeks to a few months. Decide by blood work, digestion, and well-being, not by the calendar.

What the evidence offers

There are no controlled long-term trials of strict carnivore. The first randomized trials have only been registered and run for weeks to months: one in Liverpool compares carnivore with a Mediterranean diet over three weeks (NCT07462871), another in inflammatory bowel disease and rheumatoid arthritis runs for two twelve-week phases (NCT07524244). Neither has published results yet. The authors of the largest survey also write that the long-term effects of this diet still need to be studied. There are two kinds of data, and neither says much about the right duration.

The largest source is an online survey of 2029 adults (Lennerz et al., 2021). Only people who had already eaten carnivore for at least six months could take part. The median was 14 months, with a range from 6 to 337 months. Most reported high satisfaction. Among those who reported current lipid values, median LDL cholesterol was markedly elevated at 172 mg/dL. All of it is self-reported. And people who had bad experiences and stopped weren't in the survey at all.

The best-known physician-supervised observation is older: in 1928 and 1929, two men at Bellevue Hospital in New York ate only meat for a year (McClellan and Du Bois, 1930). The authors found no signs of kidney damage or vitamin deficiency during that year. Still, two people over one year is a case observation, not a statement about everyone.

Why the calendar is the wrong yardstick

"30 days", "90 days", or "forever" are formats, not study results. Whether carnivore still suits you after three months is something you'll notice in yourself, not in a number someone sets for everyone.

Some use carnivore for a limited time as an elimination diet and then reintroduce single foods. Others stay with it or move to animal-based. Either way, you decide based on your own lab values.

What to decide by

• Blood work: measure once beforehand and then compare. A first check after 8–12 weeks of reasonably stable practice is a sensible point, earlier with symptoms. What belongs in it is in the recommended lab panel.
• Lipids: LDL and ApoB rise markedly in some people. How to read that is in the article “LDL and lipids on strict carnivore: evidence review”.
• Digestion: stool, bloating, diarrhea, or constipation over weeks, not just the first few days.
• Well-being: energy, sleep, performance, and whether you can keep the diet up in daily life without constant stress.

If your values clearly get worse or symptoms persist, that's a reason to change the diet, no matter how many weeks have passed. Warning signs belong with a doctor.

With pregnancy, breastfeeding, kidney disease, gout, diabetes on medication, or known lipid disorders, clear carnivore with a doctor first, even for short periods. This page does not replace advice.

Further reading

• The first 30 days
• Recommended lab panel: which blood values to check
• LDL and lipids on strict carnivore: evidence review
• Carnivore vs animal-based: the difference
• Red flags: when to see a doctor