A Low-Carb Diet May Not Help You Lose Weight, a Study Finds

According to certain research, reducing your intake of carbohydrates can help you reach your weight loss objectives. However, recent studies suggest that weight loss may not be achieved with some low-carb diets.

Three distinct studies involving over 67,000 participants were the subject of a study published in JAMA Network Open. Pre-existing chronic conditions were absent, all participants in the three studies were under 65 years of age, and they were all deemed healthy. By self-reporting diet details and any weight gain or loss at four-year intervals, participants provided data.

The results of five distinct low-carb diets, each of which reduced daily carbohydrate intake to between 38% and 40%, were compared by the researchers. A general low-carbohydrate diet, one that prioritized animal protein and fat, another diet that concentrated on protein and fat from vegetables, a low-carb diet that emphasized eating less refined carbohydrates, more plant protein, and healthy fats like olive oil, and lastly, a "unhealthy" meal plan that included more animal protein, refined grains, and "unhealthy" fats were all contrasted in the study.

Researchers discovered that low-carb diets emphasizing the consumption of high-quality macronutrients from wholesome plant-based foods were linked to lower rates of weight gain, while low-carb diets emphasizing refined carbohydrates or proteins and fats sourced from animals were linked to higher rates of weight gain. Those who were younger, heavier, and less active showed stronger correlations with these variables.

In other words, individuals who consumed a low-carb diet high in meat gained more weight over time than those who consumed a diet high in plants.

Though there isn't a single, accepted definition of "low carb," Melissa Prest, D.C.N., R.D.N., national media spokesperson for the Academy of Nutrition and Dietetics and member of the Prevention Medical Review Board, says it's generally understood to refer to a diet that limits starchy vegetables like potatoes, grains, and fruits that are high in carbohydrates. "Most individuals adhering to a low-carb diet will prioritize selecting foods that are higher in fats, protein, and non-starchy vegetables, such as leafy greens," she continues.

According to award-winning nutritionist and Sunsweet partner Toby Amidor, M.S., R.D., C.D.N., "A healthier low-carb diet can consist of 45% of total calories from carbs which is between 900-1300 calories or 225-325 grams of carbs based on a 2,000 calorie diet." This is what a low-carb diet looks like. According to Amidor, this lower-carb diet permits the consumption of a range of whole foods high in carbohydrates, such as fruit, whole grains, legumes, and dairy products, ensuring that the body gets the nutrients it requires to maintain health.

Some low-carb diets—like the keto diet—significantly reduce the amount of carbohydrates consumed. According to Amidor, "these low-carb diets are unhealthy because not enough nutrients are consumed to keep the body in optimal health."

Although ultra-processed meats like bacon, salt, and saturated fat are regarded as low-carb foods, Prest notes that these foods have been associated with heart disease, cancer risk, and inflammation. Lean meats, unsaturated and monounsaturated fats from nuts and seeds, and lower-carb veggies like broccoli, cauliflower, cabbage, and leafy greens are better options when preparing a low-carb meal.

A low-carb diet is not the same as a no-carb diet, according to registered dietitian Keri Gans, M.S., R.D., author of The Small Change Diet. She says, "Remember that low-carb diets can, and should, still contain carbohydrates, especially those with health benefits."

Gans advises speaking with a registered dietitian or your primary care physician if you're thinking about going low-carb to make sure you're still getting the nutrients your body needs. Amidor adds that people who have problems with their kidneys, liver, gallbladder, or pancreas—particularly those who have certain forms of diabetes—should speak with a doctor before beginning a carbohydrate restriction.