A recent study analyzed the calorie and nutrient levels provided by well-planned low- and very-low-carbohydrate diet plans, suggesting they can meet some of the nutrient needs of certain populations, particularly middle-aged women. However, these diet plans may lack 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. Low-carbohydrate diets are increasingly popular despite ongoing debates about the diet’s nutritional value and long-term health effects. A new study published in Frontiers in Nutrition assessed the calorie and nutrient content of three well-planned 7-day low-carb diet plans. However, none of the low-carbohydrate meal plans could meet all of the calorie and nutrient needs of each studied gender and age group, raising concerns about the diet’s overall nutritional adequacy.
Typically, low-carb diets involve consuming less than 130 grams of carbohydrates daily, which can be less than 26% of a person’s daily calorie intake. Very low-carbohydrate diets are even more restrictive, with only 20–50 grams of carbohydrates per day, representing less than 10% of daily calories. The researchers developed specific diet plans with varying carbohydrate levels and nutrient contents to assess how well they met recommended dietary allowances for different age groups. They found that while the plans generally provided adequate calorie intake for middle-aged women, they failed to meet daily calorie needs for men across both age groups. 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, but fell within acceptable ranges. The plans provided ample vitamins for both men and women, including vitamin A, C, D, E, and B vitamins, without exceeding safe limits.
The meal plans also contained adequate calcium for adults aged 31–50 but did not meet the calcium needs of older adults. Iron intake was adequate for males and older females but fell short for middle-aged women except on the 100-gram carbohydrate plan. Saturated fat made up a significant portion of total calories in each plan, but the omega-6 to omega-3 fatty acid ratio was more favorable than the average American diet. Fiber intake varied, with middle-aged males not meeting minimum recommendations while females exceeding them on the higher carbohydrate plans. Adequate fiber intake is crucial for maintaining a healthy intestinal system and controlling cholesterol levels. The study suggests that the 100-gram carbohydrate meal plan came closest to meeting nutrient goals, particularly for middle-aged women, but still had shortcomings in key nutrients and exceeded recommended limits in others.
The research found that the benefits of a low-carbohydrate meal plan may come from the inclusion of high-quality protein sources like fatty fish, which are rich in heart-healthy omega-3s. However, excessive saturated fats from animal products could increase LDL cholesterol and cardiovascular disease risks. While animal proteins offer benefits, the overall dietary composition of a low-carb diet matters significantly. Plant-based diets that emphasize high-quality, whole foods are generally superior for cardiovascular health due to their higher fiber and phytochemical content. The study authors acknowledge limitations in their analysis, such as not using real dietary intake data to develop meal plans and not factoring in dietary supplements. They caution against personalizing meal plans without considering age, gender, physical activity, and preexisting conditions.
Although low-carb diets may be nutritionally adequate for certain groups when carefully planned, the challenge lies in building high-quality, well-balanced diets in real life. Many low-carb diets rely on ultra-processed products which may not offer the same health benefits as whole, nutrient-dense foods. Ensuring that low-carb diets consist of high-quality, minimally processed foods is crucial for achieving the best health outcomes. While the study’s meal plans were deemed nutritionally adequate, they may not fully address the practical difficulties individuals face in adhering to such diets over extended periods. Overall, the study highlights the importance of considering nutrient adequacy, long-term sustainability, and adherence when evaluating low-carbohydrate diet patterns for optimal health outcomes.
