- Due to their restrictive nature, low-carb diets, which contain less than 130 grams of carbohydrates per day, are often viewed as nutrient deficient diets.
- However, a recent study has shown that well-planned low-carb and very low-carb diets can be a good complement to the nutritional needs of certain populations, particularly middle-aged women. This suggests that these diets can meet nutrient needs.
- While these diet plans may offer some benefits, they don’t seem to meet everyone’s nutritional needs. They may be missing some important nutrients while exceeding recommendations for others.
- More research is needed, but health experts recommend a moderate to high consumption of carbohydrates from nutrient-rich, plant-based foods for optimal health.
Low-carb diets are becoming increasingly popular, despite ongoing debate about the nutritional value of this diet and its long-term health effects.
Now, adding to the discussion, a new study has been published in Limits in nutrition assessed the calorie and nutritional content of three well-planned 7-day low-carb diet plans.
However, no low-carb meal plan could meet the total calorie and nutrient needs of the sexes and age groups studied.
The study received funding from Simply Good Foods USA, Inc., owner of Atkins and Quest Nutrition, brands that sell low-carb food products.
In addition, two of the study’s three authors are official employees and one is a shareholder of Simply Good Foods USA, Inc.
Medical news today contacted Simply Good Foods for comment regarding the funding of the research 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 diet pattern modeling using publicly available datasets and assisted in writing the manuscript, together with an external expert. The study underwent peer review to ensure the scientific integrity of the work.”
Clinthorne further stated:
“The purpose of this study was to determine whether different levels of carbohydrate restriction can provide adequate nutrition, as this is a common question regarding low-carb diets. The study uses dietary pattern modeling, which is an easily repeatable process for the research community, it underwent peer review to ensure the scientific integrity of the work, and we followed the COI disclosure practices required by the journal. The study also transparently shows both the nutrients of adequacy and of concern when following these types of dietary patterns, which can help advance the scientific dialogue about low-carb diets.”
Typically, a low-carb diet involves consuming less than 130 grams (g) of carbohydrates per day, which is less than 26% of a person’s daily calorie intake.
Very low-carb diets are even more restrictive, with only 20-50 grams of carbohydrates per day. This represents less than 10% of daily calories.
The researchers developed three specific diet plans, each containing 20, 40, or 100 grams of net carbs and varying amounts of other nutrients and calories daily.
Net carbs refer to the carbohydrates that are digestible by humans. They are calculated by subtracting fiber and sugar alcohols from the total carbohydrates on a food label.
The foods have been deliberately selected to
The researchers assessed how well these plans met the recommended daily allowance for men and women aged 31 to 50 and 51 to 70.
For women, the three 7-day low-carb meal plans generally met or exceeded daily calorie needs. Only the 100-gram-carb plan fully met the calorie needs of middle-aged women, while for older women it was even higher.
In contrast, in men in either age group, none of the meal plans met the recommended daily calorie intake.
The meal plans, which substituted fats for carbohydrates, were naturally higher in fat and lower in carbohydrate levels than generally recommended. Protein intake in these meal plans was above the recommended daily allowance for both genders, but within the acceptable macronutrient range.
Both men and women of all ages would get more than enough of several vitamins, including A, C, D, E, K, thiamin, riboflavin, niacin, B6, folic acid, and B12, without exceeding safe upper limits on these plans.
The plans also provided adequate calcium for adults ages 31 to 50, but did not meet the calcium needs of older adults.
Iron intake from these meal plans was adequate for men and older women, but middle-aged women, who need more iron, would not get enough iron except from the 100-gram carbohydrate plan.
Saturated fat made up a significant portion of the 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, often a concern with low-carb diets, showed mixed results. Middle-aged men would not meet the minimum fiber recommendations on these meal plans, while women would exceed them on the 40- and 100-gram carbohydrate diets. Older women and men on the higher-carb plans would also meet fiber requirements.
Adequate fiber intake is necessary for a healthy intestinal tract and to keep cholesterol levels under control.
The 100-gram carb meal plan, the least restrictive, came closest to meeting nutritional goals, especially for middle-aged women. However, even as a well-planned diet, it still falls short in some key nutrients while exceeding recommended limits in others.
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 100-gram carbohydrate meal plan described.
The 7-day low-carb diet plan included animal products at almost every meal, such as eggs, dairy, meat, poultry, or fatty fish such as salmon, mackerel, sardines, or tuna.
Holland noted that the benefits of a similar meal plan “may come primarily from the addition of high-quality protein sources such as dark, fatty fish,” which provide heart-healthy omega-3 fatty acids that have been linked to slower cognitive decline and a lower risk of heart disease.
Regular consumption of fatty fish likely led to the desired omega-6 to omega-3 ratio in the meal plans.
However, the saturated fats from full-fat dairy products and red meat, which exceed recommended levels, can increase LDL cholesterol (bad cholesterol) and the risk of heart disease.
“Therefore,” Holland said, “although animal proteins are beneficial, the type of animal protein and the overall composition of the diet are very important.”
In general, when considering a diet for optimal health, Holland stated the following:
“While a low-carb diet high in animals can offer some benefits, especially if it includes healthy protein sources like fish, a plant-based diet that emphasizes high-quality, whole foods is generally better for cardiovascular health, particularly because of its higher fiber and
phytochemical contents.”
The study authors acknowledge that this analysis has limitations. For example, it does not use data on actual food intake of free-living individuals to develop meal plans based on more commonly consumed foods. It also does not take into account dietary supplements.
They caution that, as with any meal planning for specific populations, meal plans and research results should not be personalized without taking into account age, gender, physical activity and pre-existing conditions.
Alyssa Simpson, RDN, CGN, CLT, a registered dietitian, certified gastrointestinal nutritionist, and owner of Nutrition Resolution in Phoenix, AZ, who was not involved in the study, said MNT that while the research shows that low-carb diets can be nutritionally adequate for certain groups when carefully planned, “the challenge lies in whether people actually build a high-quality, well-balanced diet in real life.”
“Many low-carb diets rely on ultra-processed products, which may not provide the same health benefits as whole, nutrient-dense foods,” she pointed out.
She noted that, for example, ultra-processed foods such as “low net carb bars and shakes can be convenient for people following a low-carb diet, but it’s essential to choose products with high-quality ingredients and minimal artificial sweeteners.”
Simpson said that “ensuring that low-carb diets are both nutritionally complete and consist of high-quality, minimally processed foods is critical to achieving the best health outcomes.”
Ultimately, she concluded the following about the low-carb diet patterns in this study:
“While low-carb diets may offer benefits, their long-term sustainability and adherence can be challenging. The study’s meal plans, while nutritionally adequate, may not fully address the practical challenges individuals face in adhering to such diets for extended periods of time.”