Simply Good Foods-backed research supports healthiness of low-carb diets

11 Sep 2024 --- A well-constructed low-carbohydrate diet can meet and even exceed people’s nutrient needs, according to a new modeling study. As these eating patterns are growing popular to support overall health and manage or reverse type 2 diabetes, skepticism remains about their nutritional quality. For example, critics note that they could lead to overconsumption of protein or fat and under-consumption of essential nutrients.

Researchers find that three low-carb meal plants (containing less than 130 g of carbs daily) exceed nutrient needs for vitamins A, C, D, E, K, thiamin, riboflavin, niacin, folate and vitamins B6 and B12 for men and women aged 31–70. 

They assessed the nutrient adequacy of three different seven-day low-carb meal plans: two ketogenic diets providing 20 g or 40 g of net carbs daily and one more liberalized plan containing an average of 100 g of net carbs per day. The team calculated net carbs as total grams of carbohydrates minus grams of fiber consumed. 

Nutrition Insight discusses the study’s outcomes and implications with Jonathan Clinthorne, Ph.D., senior director of nutrition at Simply Good Foods — which provided funding for the study — and co-author of the study. 

“We are an organization that has its roots in nutrition science and educating consumers on eating well. Our primary goal was to utilize our unique knowledge on how to construct different low-carbohydrate eating plans to contribute to the greater body of literature on low-carbohydrate diets,” says Clinthorne.

He adds that much research has revealed different therapeutic uses for low-carbohydrate diets. “Our goal was to demonstrate that these diets meet or exceed the intake of key nutrients for the US public.” 

“At its core, this was a modeling study evaluating the nutrient density of well-constructed low carbohydrate approaches. More research is needed to understand how the modeled diets compare to the food consumed by people following low carbohydrate approaches.” 

Low-carb diets can help improve blood sugar and reduce the need for drugs in people with prediabetes or type 2 diabetes.Blood sugar benefits

According to the study, research supports the benefits of low-carb diets in epilepsy, chronic diseases such as type 2 diabetes, polycystic ovarian syndrome, metabolic syndrome and overweight and obesity. 

Clinthorne adds: “Low-carbohydrate diets have been viewed by the public as a quick weight-loss tool, but this approach has a substantial amount of evidence showing how they can help improve blood sugar and reduce the need for medications in people with prediabetes or type 2 diabetes.” 

“This evidence has led the American Diabetes Association to provide low-carbohydrate diets as a viable option for people with diabetes,” he underscores. 

“Because the foundational mechanism by which low-carbohydrate diets work is by reducing blood sugar fluctuations and insulin, there has even been a broader adoption of this dietary philosophy as a tool for managing various metabolic-related diseases.”

Low-carb meal plans

A low-carbohydrate pattern contains less than 130 g or 10–25% of energy from carbohydrates daily, while very low-carb diets have 20–50 g or less than 10% of energy from carbohydrates daily. 

For the study published in Frontiers in Nutrition, the researchers created three seven-day meal plans consisting of different meals for breakfast, lunch, dinner and a snack, using foods listed in the USDA Food Data Central. This comprehensive source of food composition data includes commodity and minimally processed food samples, experimental foods, branded foods, foods and drinks widely consumed in the US and historical data. 

The research team compared the average intake of energy, carbs, fiber, protein, fat and micronutrients to the Recommended Dietary Allowance (RDA) for females and males aged 31–50 and 51–70. 

Clinthorne highlights that the research puts the misconception to rest that a low-carb eating pattern cannot provide adequate nutrition. “Our analysis of three different levels of carbohydrate restriction demonstrated that these diets are nutritionally replete and far superior to the average diet for delivering essential nutrients.” 

One breakfast was scrambled eggs, mushrooms and zucchini, adding tomatoes and whole wheat toast for a higher-carb meal.The study reveals that all meal plans met or exceeded estimated average micronutrient requirements for women aged 31–50, which the researchers note is “the population group most likely to consume low-carbohydrate diets.” 

Moreover, the meal plans exceeded RDAs for protein for all population groups but remained in the Acceptable Macronutrient Distribution Range of 10–35% of energy. The study also concludes that none of the meal plans contributed meaningful amounts of added sugar, providing less than 0.5% energy from added sugars. 

Fiber consumption

They met or exceeded fiber recommendations for women aged 31–70 and were adequate for males aged 51–70. Although the plans did not meet fiber RDA for middle-aged men, the researchers note that meal plans provided less than 1,800 kcal daily while the energy RDA for this group is 2,200 kcal. 

The meal plan “can deliver adequate dietary fiber” when adjusting for this higher calorie intake. 

The study’s co-author, Beth Bradley, Ph.D., from the department of nutrition and food sciences at the University of Vermont, US, highlights that the data proves that low-carb diets are not necessarily low in fiber. 

“High-fiber foods are an important part of a low-carb lifestyle, partly because fiber-rich food choices can help lower net carbohydrate intake. Non-starchy vegetables, nuts and seeds, and, in moderation, even higher-carb fruits, starchy vegetables and whole grains can contribute fiber to the diet while keeping overall net carb intake in check, especially in the more liberal low-carb approach.”

Salt and fat intake

Although the plans exceeded the saturated fat and sodium recommendations, the researchers stress that these levels were lower than those in the average US diet. The plans also had more favorable omega-6 to omega-3 and sodium-to-potassium ratios than typical US diets.

Bradley underscores that where food nutrients come from and how they fit into a broader diet play important roles in determining health outcomes. 

“A better omega-6 to omega-3 ratio has been linked to a lower risk of cardiovascular disease and type 2 diabetes. And similarly, a more optimal sodium to potassium ratio may help lower the risk of high blood pressure and heart disease.”

Clinthorne highlights the importance of understanding how the modeled patterns compare to real-life diets.The plans only fell “slightly” short for nutrients in some sub-populations, such as calcium and iron. “Calcium recommendations increase for older adults ages 51–70 years of age, and all three diets fell short of meeting the RDA in these population groups,” details the study.

The meal plans with 20 g and 40 g of fiber “fell short of the RDA for iron in females aged 31–50 for whom the iron requirement is higher.” 

Real-life diet

Despite the study’s promising results, the authors caution that they did not use data from actual dietary intake to construct meal plans based on the most commonly consumed foods. They also did not consider dietary supplement intake. 

Clinical trials comparing the effectiveness and safety of weight-loss diets have criticized these plans for their short durations and low adherence. 

“We did not specifically test these plans for adherence,” asserts Clinthorne. “However, we modeled out three different carbohydrate restriction levels to demonstrate that stricter and more flexible low carbohydrate diets can provide sufficient nutrition.”

The researchers underscore the importance of adequate education, resources and support in successfully implementing low-carb diets. 

“It would be great to understand how the modeled dietary patterns compare to the diets of free-living consumers following a low carbohydrate lifestyle,” Clinthorne concludes. “This would allow for better messaging around important foods to incorporate into a low-carbohydrate lifestyle to meet nutritional needs.”

By Jolanda van Hal