Can eating nothing but meat actually be healthy? The real dangers and upsides of restrictive diets

The scales of trends always seem to seek balance. As more Americans than ever are leaning their diets in a more plant-based direction, inevitably, so the carnivore diet rises.

A recent feature in Discover explored the pros and cons of existing solely on animal products — and raised the eternal questions around the wisdom of intensely restrictive diets. For everyone who's grown up with — and struggled with — the tyranny of food pyramid and the notion that abundant, expensive variety is the key to good health, could whittling your grocery list way down instead be a better option?

The carnivore diet is exactly like it sounds — just meat, fish, poultry, dairy and eggs. You can, in some cases, jazz things up with certain spices, but that's it. Kind of makes Whole 30 look like the Golden Corral.

It's just the latest restrictive diet in a history of wellness trends that's taken us from cabbage soup to grapefruit to raw food to fruitarianism to weight loss shakes and juice cleanses. And like its predecessors, there may be at least some short term benefits. As Christopher Gardner, director of nutrition studies at the Stanford Prevention Research Center, told Discover, "One of the main things they’re doing on that carnivore diet is they’re getting rid of all their added sugar and refined grain. That is 40 percent of the American diet, and getting rid of that has got to do good things for your health." And I'll admit that when a friend of mine told me not long ago that she'd embarked on a carnivore diet, I was intrigued by her glowing energy and enthusiasm. I also somehow wanted to beg her to eat an orange. 

For the omnivorous among us — and the Catholic school survivors — the thought of putting anything off limits immediately makes it all just that much more appealing. But restrictive diets can be helpful for people looking to readjust their relationship with food. Josh Schlottman, a certified personal trainer and a nutrition coach, says that in certain situations, "Highly restrictive diets like the carnivore diet can be beneficial for a few reasons." For example, he says, "It’ll first help eliminate bad foods you would otherwise eat with a more lenient diet. If you’re only allowed to eat certain foods, eating junk foods won’t be an option." In the meantime, he says, by "eliminating foods that could possibly negatively affect you" you may discover underlying food sensitivities and gut issues. Finally, he says that for some people, restriction is simpler than calorie counting, and that "While some people like the option of eating their favorite foods, you could still be eating foods that negatively affect your body despite being low-calorie."

Total Shape fitness coach Benedict Ang also acknowledges that "One potential benefit of these plans is the quick initial weight loss they often promise. For individuals looking to shed pounds rapidly for a specific event or goal, these plans can provide a sense of immediate gratification. Additionally, some people find that strict dietary structures help them develop discipline and control over their eating habits."

But, he warns, "The promises made by these plans need to be critically examined. Most often, they claim rapid weight loss, sometimes even in a matter of days. It's essential for individuals to recognize that such drastic changes are often unsustainable and may lead to the loss of muscle mass and essential nutrients. Plus, these plans may not promote long-term lifestyle changes, potentially resulting in a cycle of yo-yo dieting." Significantly, he also points out that there's an emotional and psychological side to consider. "Such diets may contribute to the development of disordered eating patterns and a strained relationship with food," he says. "Social and psychological implications must not be overlooked either, as these plans may lead to feelings of isolation, frustration, and an unhealthy fixation on food."

Alanna Kate Derrick, a certified personal trainer, endurance sports nutrition coach and senior contributor at Gold BJ, advises healthy skepticism and common sense before starting any new diet. "These super restrictive plans grab headlines because they seem to deliver jaw-dropping transformations," she says. "What's often left out though are the struggles and health risks that come with extreme calorie cutting, off-limits food groups, or complicated rules. The thing is, losing weight isn't about deprivation or perfection. It's about progress through developing lifestyle habits you can actually enjoy long-term. This prevents the rebound weight gain that happens when people inevitably return to normal eating after a restrictive diet."

"My advice?" Derrick asks. "Be wary of any plan eliminating entire food groups or requiring complicated phases and points systems. Not only can this lead to nutritional deficits, but it isn't practical for real life. The most successful path is finding simple, sustainable changes and providing enough calories, protein, fruits, veggies, and treats so you stick with it. Rather than imposing rigid, off-limits rules that often trigger feelings of deprivation, it’s wise to take an intuitive approach and choose nourishing foods that satiate your body’s true needs. This empowers you to discover sustainable habits you can genuinely enjoy long after reaching your goals. That’s the ticket to lasting success." Ro Huntriss, Chief Nutrition Officer and RD at the wellness and intermittent fasting brand Simple, likewise offers the insight that "How you maintain weight loss is just as important as losing it in the first place. These types of plans don't often offer a sustainable way to maintain weight loss long-term and there is a risk of regaining the weight quickly once the plan is stopped." She adds that "Highly restrictive diets can also lead to social isolation, so it is important to consider how intense and restrictive diet plans would fit in with your work, social or family life."

And while all restrictive diets have their drawbacks, the carnivore diet presents unique concerns. Tricia Best, a registered dietitian at Balance One, says that "The carnivore diet may be harmful to gut health." She explains, "The diet lacks fiber, which is important for promoting the growth of beneficial gut bacteria and maintaining a healthy digestive system. Without sufficient fiber, gut bacteria may feed on the mucus lining of the gut, which can lead to inflammation and damage to the intestinal lining. The high protein content of the diet can increase levels of certain bacteria that produce harmful byproducts such as ammonia and hydrogen sulfide. These byproducts can irritate the gut lining and cause inflammation. Finally, the high fat content of the diet can also disrupt the balance of gut bacteria and contribute to gut inflammation."

It can be intriguing to declutter one's diet, to seek to spark joy by going intensely minimalist. I definitely never want to do the math on how many portions of lean protein and how much fiber I'm still "supposed to" consume each day. So I can understand the appeal of saying, screw it, I'm just eating steak and nothing but steak — even without the implied promise of better fitting jeans. 

But Hailey Gorski, a Santa Monica registered dietitian who specializes in weight loss, puts it in perspecirtve. "Strict diets can result in deficiency of essential nutrients such as vitamins, minerals, fiber, and other nutrients that are crucial for long term health," she explains. And ultimately, she says, while these plans "can create rapid weight loss," she advises, "If you create lasting changes, you'll get lasting results. Lasting changes allow for more flexibility and empowering food decisions. Temporary changes lead to temporary results." 

An earlier version of this story attributed a quote by Alanna Kate Derrick to Ro Huntriss. It has since been corrected.