The risks of the carnivore diet depend on whether you’re following the approach to lose weight or to address an autoimmune or inflammatory condition.
That said, “There are a lot of downsides to the carnivore diet,” says Liz Weinandy, RD, dietitian at The Ohio State University Wexner Medical Center in Columbus. “We have multiple food groups for a reason: They each provide us with a range of nutrients,” she says.
Eating only one food group is a problem, no matter which one (even if it’s just vegetables). Limiting yourself to all meat can cause you to run low in certain nutrients that are abundant in plants, like vitamin C and vitamin E, she says.
Although some anecdotal reports suggest that constipation isn’t a problem on a carnivore diet, you are missing out on fiber, a nutrient important for colonic health, says Weinandy. A diet high in red and processed meats has also been linked to an increased risk of gastric cancer, noted the International Agency for Research on Cancer in a study published in December 2015 in the journal The Lancet. (4) (Yet a meta-analysis of 42 studies published in May 2017 in the journal Oncotarget reported that while case-control studies on red and processed meat consumption do show this association, cohort studies — a type of observational study — do not.) (5) Eating a large amount of meat protein can also put undue stress on kidneys.
Another consideration: Extreme restriction or labeling foods “good” or “bad” can also set off disordered-eating behaviors or full-blown eating disorders, Weinandy says.
What’s more, eating an abundance of fruits and vegetables has been found to be linked to increased happiness, life satisfaction, and well-being. (6)
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What if You Opt for Lean Meats, Like Fish and Poultry?
Practically speaking, you’d have to eat a lot more to reach the same calorie level if you’re aiming to focus on lean poultry or fish choices (like chicken breast and cod). This may also prevent you from entering into ketosis, which is a goal of many people who go on very low or zero-carb diets. If you want to be in ketosis, you’d need to opt for fattier meats rather than filling up on skinless chicken breasts, but again, there is limited research on how healthy this is overall.
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