Low-carbohydrate diets are often criticized for being nutrient-deficient due to their restrictive nature, providing less than 130 grams of carbohydrates per day. However, a recent study published in Frontiers in Nutrition suggests that well-planned low- and very-low-carbohydrate diets can meet some of the nutrient needs of certain populations, particularly middle-aged women. These diet plans may offer benefits, but they do not seem to meet the nutrient needs of all individuals equally, lacking some key nutrients while exceeding recommendations for others. Health professionals recommend sticking with moderate to high consumption of carbohydrates from nutrient-dense, plant-based foods for optimal health.
The study assessed the calorie and nutrient content of three well-planned 7-day low-carb diet plans, funded by Simply Good Foods USA, Inc., the parent company of Atkins and Quest Nutrition. Two of the three study authors have declared conflicts of interest, as they are employees or shareholders of Simply Good Foods. The goal of the study was to determine whether different levels of carbohydrate restriction could provide adequate nutrition. The plans varied in net carbohydrates provided daily and were designed to address nutrients of public health concern identified in the Dietary Guidelines for Americans. The researchers assessed how well these plans met the recommended dietary allowances for different gender and age groups.
The results showed that the low-carbohydrate meal plans generally met or exceeded daily calorie needs for women but failed to meet the calorie requirements for men across both age groups. All of the meal plans replaced carbohydrates with fats, resulting in higher fat and lower carbohydrate levels than generally recommended. Protein intake was above the recommended daily allowance for both genders, while some nutrients like vitamins A, C, D, and E were provided in adequate amounts. However, some key nutrients, such as calcium, iron, and fiber, were lacking in certain meal plans, especially for middle-aged women who require more iron.
The 100-gram carbohydrate meal plan was the least restrictive and came closest to meeting nutrient goals, particularly for middle-aged women. This plan included animal products at nearly every meal, such as dark, fatty fish rich in heart-healthy omega-3s. While the inclusion of fatty fish improved the omega-6 to omega-3 ratio in the meal plans, the saturated fats from full-fat dairy and red meats could increase cardiovascular disease risks. Therefore, while animal proteins offer benefits, the type of animal protein and overall dietary composition are crucial for optimal health.
Despite the study’s findings on the nutritional adequacy of low-carbohydrate diets, limitations should be considered, such as not factoring in real dietary intake data and dietary supplements. Registered dietitian Alyssa Simpson emphasized the importance of building high-quality, well-balanced diets in real life, as many low-carb diets rely on ultra-processed products. Ensuring that low-carb diets consist of high-quality, minimally processed foods is essential for achieving the best health outcomes. While low-carb diets may offer benefits, their long-term sustainability and adherence can be challenging, as the study’s meal plans may not fully address the practical difficulties individuals face in maintaining such diets over extended periods.
