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- Due to their restrictive nature, low-carbohydrate diets that provide less than 130 grams of carbohydrates per day are often considered nutrient-poor diets.
- However, a recent study analyzed the calorie and nutrient content of well-planned low- and very-low-carbohydrate diets. The results suggest that these diets may partially meet the nutrient needs of certain populations, particularly middle-aged women.
- While these diet plans offer some benefits, they do not appear to meet the nutritional needs of all individuals equally, as they may be lacking in some key nutrients while exceeding recommendations for others.
- While more research is needed, health experts recommend maintaining a moderate to high intake of carbohydrates from nutrient-dense, plant-based foods for optimal health.
Despite ongoing debates about the nutritional value and long-term health effects of these diets, low-carbohydrate diets are becoming increasingly popular.
A new study now contributes to this discussion, which was published in Limits of nutrition evaluated the calorie and nutrient content of three well-planned 7-day low-carb diet plans.
However, none of the low-carbohydrate diets could meet the entire calorie and nutrient needs of the gender and age groups studied.
The study was funded by Simply Good Foods USA, Inc., the Atkins company, and Quest Nutrition, brands that sell low-carbohydrate foods.
In addition, two of the three study authors are declared employees and one is a shareholder of Simply Good Foods USA, Inc.
Medical news today Simply Good Foods has asked for comment on the funding of the study and reported conflicts of interest.
In response, Jonathan Clinthorne, PhD, study author and senior director of nutrition at Simply Good Foods, said: MNT that: “The funder designed and analyzed the dietary pattern modeling using publicly available data sets and helped write the manuscript together with an outside expert. The study was peer-reviewed to ensure the scientific integrity of the work.”
Clinthorne further explained:
“The goal of this study was to determine whether varying degrees of carbohydrate restriction can ensure adequate nutrition, as this is a common question with low-carb diets. The study uses dietary pattern modeling, which is an easily repeatable process for the research community. It was peer-reviewed to ensure the scientific integrity of the work, and we followed the journal’s required disclosure practices for COI. The study also transparently highlights both the nutrients that are adequate when following these types of dietary patterns and those that are of concern, which may help advance the scientific dialogue about low-carb diets.”
Typically, a low-carbohydrate diet involves consuming less than 130 grams (g) of carbohydrates daily, which is less than 26% of a person’s daily calorie intake.
Very low-carbohydrate diets are even more restrictive, containing only 20–50 g of carbohydrates per day, which is less than 10% of daily calories.
The researchers developed three specific diet plans, each providing 20, 40 or 100 g of net carbohydrates and varying amounts of other nutrients and calories daily.
“Net carbohydrates” are the carbohydrates digestible by humans, calculated by subtracting fiber and sugar alcohols from the total carbohydrates on a food label.
The foods were deliberately selected to
The researchers assessed the extent to which these plans met the recommended daily amounts for men and women aged 31–50 and 51–70.
In women, the three 7-day low-carbohydrate meal plans generally met or exceeded daily calorie needs, but only the 100-gram carbohydrate plan fully met the calorie needs of middle-aged women, while it exceeded the needs of older women.
For men in both age groups, however, none of the diet plans were sufficient to cover the recommended daily calorie intake.
The diets that replaced carbohydrates with fats naturally contained more fat and fewer carbohydrates than generally recommended. Protein intake in these diets was above the recommended daily amount for both sexes, but was within the acceptable macronutrient range.
Both men and women of all age groups would get more than enough of several vitamins on these plans, including A, C, D, E, K, thiamin, riboflavin, niacin, B6, folate and B12, without exceeding safe upper limits.
Although the plans also provided ample calcium for adults ages 31 to 50, they failed to meet the calcium needs of older adults.
Iron intake in these diets was adequate for men and older women, but middle-aged women—who need more iron—would not get enough iron except on the 100-gram carbohydrate plan.
Saturated fats accounted for a significant proportion of total calories in each plan, with 21% in the 20-gram diet, 19% in the 40-gram diet, and 13% in the 100-gram diet. However, these plans had a better
Fiber intake, which is often a problem with low-carbohydrate diets, showed mixed results. Middle-aged men did not reach the minimum recommended amounts of fiber on these diets, while women would exceed them by 40 and 100 grams on the higher-carbohydrate diets. Older women and men would also meet fiber needs on the higher-carbohydrate diets.
Adequate fiber intake is necessary to support healthy intestinal flora and control cholesterol levels.
The 100-gram carbohydrate diet was the least restrictive and closest to achieving nutrient goals, especially for middle-aged women. However, even a well-planned diet lacks some important nutrients while others exceed recommended limits.
MNT spoke with Thomas M. Holland, MD, MS, a physician-scientist and assistant professor at the RUSH Institute for Healthy Aging, RUSH University, College of Health Sciences, who was not involved in the study, to discuss the potential effects of the outlined 100-gram carbohydrate eating plan.
The 7-day low-carbohydrate diet included animal products at almost every meal, such as eggs, dairy products, meat, poultry or fatty fish such as salmon, mackerel, sardines or tuna.
Holland noted that the benefits of a similar eating plan may come “primarily from the inclusion of high-quality protein sources such as dark, fatty fish,” which provide heart-healthy omega-3 fatty acids that have been linked to less cognitive decline and a reduced risk of heart disease.
Regular consumption of fatty fish probably led to a preferred ratio of omega-6 to omega-3 in the diet.
However, saturated fats in whole-milk products and red meat, which exceed recommended limits, could raise LDL cholesterol (bad cholesterol) levels and increase the risk of cardiovascular disease.
“Although animal proteins offer benefits,” says Holland, “the type of animal protein and the overall composition of the diet play a crucial role.”
Overall, when considering a diet for optimal health, Holland found:
“While a high-animal, low-carbohydrate diet may offer certain benefits, particularly when it includes healthy protein sources such as fish, a plant-based diet that emphasizes high-quality whole foods is generally better for cardiovascular health, particularly due to its higher fiber and
secondary plant substances Contents.”
The study’s authors acknowledge that this analysis has limitations. For example, it does not use data on actual food intake in wild individuals to develop diets based on commonly consumed foods. Nor does it take into account dietary supplements.
They point out that the meal plans and study results – like any meal planning for specific population groups – should not be personalized without taking into account age, gender, physical activity and pre-existing medical conditions.
Alyssa Simpson, RDN, CGN, CLT, a registered dietitian, certified gastrointestinal dietitian and owner of Nutrition Resolution in Phoenix, AZ, who was not involved in the study, said MNT Although the study shows that low-carbohydrate diets can be nutritionally appropriate for certain groups if carefully planned, “the challenge is whether people eat a high-quality, balanced diet in real life.”
“Many low-carb diets rely on highly processed products that may not provide the same health benefits as whole, nutrient-dense foods,” she emphasized.
For example, she pointed out that highly processed foods such as “low net carb bars and shakes can be convenient for people on a low-carb diet, but it’s important to choose products with high-quality ingredients and as few artificial sweeteners as possible.”
Simpson said that “ensuring that low-carbohydrate diets are both nutritionally complete and consist of high-quality, minimally processed foods is critical to achieving optimal health outcomes.”
Finally, regarding the low-carbohydrate dietary patterns of this study, she concluded:
“Although low-carbohydrate diets may provide benefits, their long-term sustainability and adherence can be challenging. The study meal plans, while nutritionally adequate, may not fully address the practical difficulties individuals face when following such diets for extended periods of time.”
