Plus, while you’re limiting harmful processed foods, this much meat puts you well over the recommended saturated fat intake, raising your cholesterol and increasing your risk of heart disease and stroke—already two of the top five killers of men in the country.
What it is: Our body traditionally uses glucose to fuel both our muscles and our brain. When you cut your carb intake to less than 10 percent of your total calories (less than 5 percent for die-hards), the glucose deprivation forces your body to instead use fat as fuel in your workouts, and forces your brain to release ketones, a unique backup brain food that has side effects like stopping epilepsy and unbelievable mental clarity.
What the research says: In the short term, the keto diet is pretty safe and effective. Research on overweight folks has found cutting carbs and increasing fat consumption can shed excess weight, improve insulin resistance, reduce blood pressure, improve cholesterol levels, and maybe even offset type 2 diabetes risk. And it’s probably an improvement over how most Americans eat: A 2017 study in Diabetes & Metabolic Syndrome reports that for overweight and obese people, going keto and not exercising may be a healthier option, metabolically and aesthetically, than eating the standard American diet and working out three to five days a week.
But it might not be superior to other healthy diets. When overweight or obese men spent four weeks eating either keto or a healthy, high-carb diet, they burned more calories on a daily basis without the macro—but it actually took them a full month to lose the same amount of body fat on a keto diet as they lost in two weeks on the high-carb diet, according to the results published in the American Journal of Clinical Nutrition. And when it comes to healthy dudes, most research shows keto is just as effective as any other diet at reducing fat, but it compromises anaerobic, aerobic, and strength performance when you’re relying on fat as fuel rather than carbs.
And science doesn’t support eating this way long term: A recent study in The Lancet suggests limiting your carb intake in the long term can shorten your lifespan, probably because you’re cutting your fruit and vegetable intake, while another large study caution against cutting down on carbohydrates presented at the 2018 European Society of Cardiology Congress found people on the lowest-carb diets were the most likely to die from cancer, cardiovascular disease, and all other causes.
The pros: In the short term, going keto can help you get lean while retaining muscle and, because you’re consuming so much fat, you won’t be as hungry as you might be if you were restricting calories, says White. Plus, you’re cutting unhealthy carbs like donuts and pastries and you’re getting more nutrients than the carnivore diet since you’re eating at least some fruits and vegetables.
The Cons: You’ve got to count your calories, since fat has more than double the calories of protein or carbohydrates, gram for gram. And you might be more constipated and bloated—less plants means less fiber, which is crucial to support digestive function. This is compounded by high intake of hard-to-digest protein intake, White says.
The real risk, though, comes from where your fat sources come from. Since most plants are high in carbs, you’ll likely end up eating a lot of animal products which are high in saturated fat and bad cholesterol, increasing your risk of heart disease, White points out. But as keto becomes more popular, so do variations that might help offset the risks of the higher disease in the long term, like the keto-mediet which has you replace red meat and dairy with healthier, medium-chain fatty acids in coconut oil, or the newly released ketotarian diet, which is all about marrying keto with vegetarianism.
Who it’s best for: In the short term, it may be an effective and safe options for cutting, when you want to decrease fat without losing lean mass—but it’ll work against you when you’re trying to bulk. And for most athletes—especially endurance athletes—the body comp payoff of keto isn’t enough to justify how a low-carb plan will compromise your performance, White says.
High-Protein Vegan Diet
What it is: You only eat plant-based foods, avoiding all animal product while also tracking how much protein you’re getting to make sure you’re facilitating anabolic growth.
What the research says: Some studies suggest vegetarians and vegans have poorer health, but the majority of research reports becoming a vegetarian folks who avoid meat have a lower risk of heart disease, cancer, type 2 diabetes, and have a longer life span. This may be even more true when comparing veganism against most current fad diets: A recent, large study in The Lancet found people who cut carbs and upped their animal intake had a higher mortality rate than folks who eat more plant-based foods.
And despite the bad rap of plant protein, 2017 research in the American Journal of Clinical Nutrition reports that as long as men and women were getting at least the recommended daily allowance of protein (that’s 0.8 g/kg of body weight), carnivores and omnivores had roughly the same muscle mass and strength.
Meanwhile, research in Nutrients found among endurance athletes, fueling with plants or animals landed athletes with pretty much the same body composition and quality of physical performance, with carnivores clocking slightly more visceral, belly fat and omnivores logging a slightly better VO2max and comparable strength.
The pros: “Plant protein when eaten straight from the source comes packed with fiber and phytochemicals—two of the most influential compounds for long-term health,” says Matt Ruscigno, RD, co-author of No Meat Athlete. Looking at the research, it’s clear those who eat more fruits, vegetables, whole grains, and legumes have lower rates of every major chronic disease. “Optimal nutrition for athletes is about more than performance; it also includes long term health,” Ruscigno adds.
The Cons: “It’s crucial for athletes to consume enough protein to maintain muscle turnover,” says Ruscigno. Some studies suggest vegans may need to eat more of the macro to achieve the same results they’d get from the animal variety like whey, but Ruscigno adds that, aside from strength athletes, a lot of guys underestimate their protein consumption.
The main worry isn’t in getting enough protein, but instead scoring it with within your daily calorie count, says sports nutritionist Jeff Rothschild, RD. Since most vegan sources of the macro are also higher in calories, it can be hard to be a calorie-restricted vegan without relying heavily on a lot of supplemental protein powders, he points out. Since powders are more likely to accumulate toxic metals like arsenic, mercury, and pesticides, you want to stay within just one scoop a day. (Rothschild suggests checking the Clean Label Project. before you buy your plant protein.)
And you’ll have to take other supplements—a study review by Mayo Clinic physicians found vegans are most often deficient in vitamin B12, iron, calcium, vitamin D, protein, and omega-3 fatty acids. In addition to B12, iron, and an EPA/DHA supplement, vegans should add creatine and β-alanine supplementation to their routine, suggests a 2017 review in the Journal of the International Society of Sports Nutrition.
Who it’s best for: Pretty much every athlete who wants to cut his meat intake back will fare well on a high-protein vegan diet, but it’s an especially great option for guys with a family history of heart disease—forgoing meat can reduce your risk for ischemic heart disease by 32 percent.
BY RACHAEL SCHULTZ