Today’s hottest diets come with hefty lists of forbidden foods. And sure, the regulars (like cronuts, soda, and bacon) are on there, but it’s foods like milk, black beans, and sweet potatoes that leave most dieters scratching their heads.
If those foods are really so healthy, how’d they end up on the blacklists of popular eating strategies including the paleo and keto diets.
The exact reason depends on the diet you’re considering. “For example, the rationale for the food prohibitions on the paleo diet is based on the assumption that whatever our ancestors didn’t consume, we should avoid now,” says nutritionist Georgie Fear, R.D., author of Lean Habits for Lifelong Weight Loss. Examples include dairy, grains, and legumes.
Meanwhile, the pegan diet, a hybrid of the paleo and vegan diet, also excludes some meat and animal products based on health fears associated with animal products to ethical considerations regarding animal suffering or death, she says. It also prohibits high glycemic-index foods like fruit and some veggies.
The keto diet has a similar—but way more strict—focus on low-GI foods. Keto dieting is a very low-carbohydrate, high-fat style of eating, which produces a state known as ketosis to encourage weight loss. To remain in ketosis, dietary carbohydrate intake must be severely limited, with moderate protein and most of the daily calories coming from fats. “Because the keto diet does not limit calories (only carbohydrates) it is appealing to those who would like to lose weight without a restriction on total food intake,” Fear says.
“Aside from those with food allergies and intolerances, removing these food groups is largely a dietary example of throwing out the good with the bad,” she says.
tk Forbidden Foods That Are Healthy for You and Can Help You Lose Weight
Check out some of the most commonly forbidden foods that can actually be great for your nutrition and health. Here’s how much of them you should eat, and how you should integrate them into your diet, for healthy, sustainable weight loss:
1. Dairy
While many paleo, keto, and pegan dieters still consume dairy in small portions, following any of the diets to a T requires giving up dairy altogether. That’s because 1) cavepeople didn’t drink milk and 2) dairy contains carbs. But dairy also contains potassium, calcium, vitamin D, and protein, all of which can help you lose weight and live healthier, says registered dietitian Vandana Sheth, R.D.N., a spokesperson for the Academy of Nutrition and Dietetics. According to a 2012 International of Obesity meta-analysis of randomized controlled clinical trials, people who enjoyed the most dairy while on a low-calorie diet experienced greater fat loss and increased muscle mass when compared with those that had lower dairy intake.
“Eating less ice cream might be a dietary improvement, but banning dairy foods entirely is not warranted by the scientific literature. While it is possible to obtain enough protein and calcium from other sources, evidence links dairy intake to many positive health outcomes,” Fear says. What’s more, whey protein contained in dairy has been shown to be one of the best proteins for helping muscles recover after a tough workout, Fear says. She recommends that, as long as you aren’t lactose-intolerant, you consume two to three servings of dairy per day.
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2. Beans and Legumes
Beans and legumes are forbidden foods on the paleo diet, which claims that they wreak havoc on the human body. (Whole30 nixes them for similar reasons.) Meanwhile, the pegan and keto diet both exclude them for their carb content. But, whole carbs are healthy, and so are all of their B vitamins, iron, and zinc. “Beans and legumes are sources of vitamins, minerals, and fiber, and exclusion of these from diet offers no supported health benefits. Eating more of these foods is linked to less chronic disease, healthier body weight, and increased longevity,” Fear says. For instance, a 2014 study published in Obesity found that eating a single serving a day of beans and legumes can increase fullness and lead to weight loss. Study researchers suggest eating at least 3/4 cup of legumes per day.
3. Whole Grains
“It is a dietary improvement to reduce reliance on granola bars and refined grain snack foods, however, excluding all grains, including whole grains, removes many nutrients from the diet,” Fear says, who notes that skipping all grains can make it hard for athletes to get enough carbohydrates to fuel activity, while reducing intake of fiber and energy-revving B vitamins. Still, the paleo, pegan, keto all ban whole grains—and the gluten-free diet excludes most of them. However, some anthropologists are now suggesting that some whole grains may have been part of our ancestors’ diet. U.S. Dietary Guidelines recommend that all adults eat three to five servings of whole grains per day.
4. Sweet Potatoes
No matter where you stand on the white potato debate, you have good reason to love sweet potatoes. They are rich in the powerful antioxidant beta-carotene, not to mention potassium, fiber, vitamin A, B vitamins, and even some protein, Sheth says. You don’t have to eat them every day, or ever for that matter, but if you like them, they can be a yummy and healthy part of any moderate-carb diet, Fear says. Just make sure not to drown them in butter and brown sugar.
5. Spices
Honestly, what offense can any diet take with spices? Well, on the keto diet, carbs. “Limiting the flavor of your food to avoid an extra gram of carbohydrates may be a sign your diet is a bit too rigid, if you ask me,” Fear says. “Spices are not required in the diet, however many are rich sources of bioactive compounds that do everything from preventing cancer, to improving blood vessel function and reducing inflammation.” Bonus: they add flavor and contain virtually zero calories, Sheth says. Sprinkle this forbidden food to your heart’s content.
6. Fruit
Pretty much all fruit are forbidden foods if you’re following a keto diet, and especially sugary varieties such as bananas, melons, and pineapples are banned on some low-GI diets that only allow for berries. “I don’t believe this level of restriction benefits the dieter any, other than providing a sense of virtue by means of excessive control,” Fear says. Fruit provides many of the same nutritional benefits as vegetables, including vitamins A, C, fiber, and antioxidants for minimal calories. Shoot for eating several servings each and every day.
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7. Peppers
Peppers, carrots, squash, and peas are also forbidden foods on the keto diet since they will knock a person out of ketosis due to their carbohydrate content, Fear says. (FYI, one medium bell pepper contains 6 grams, a far cry from white bread’s 45.) Meanwhile, beets, pumpkins, all potatoes, and parsnips are banned on the pegan diet, since they rank above 69 on the glycemic index. As long as you take their carb intake into account, and don’t serve starchy vegetables like squash alongside your pasta, there’s no reason not to incorporate these veggies into your daily diet. After all, any healthy eating plan should have you eating more, not fewer, veggies. People who eat at least seven servings of fruits and veggies per day reduce their risk of dying from any cause—at any point in life—by 42 percent, according to one large-scale 2014 study in the British Medical Journal.