Despite the many people who follow a low-calorie diet, only 20% of overweight and obese adults report maintaining weight loss over the long term. Overweight and obese people are often at high risk of other chronic diseases such as cardiovascular disease and type 2 diabetes. To address this issue, the impact of low energy foods and functional foods on these factors needs to be explored.
Diets with low energy density may help to increase satiety and reduce overall energy intake. Studies are limited in their impacts on weight maintenance.
Functional foods are defined as a food or ingredient that provides additional health benefits beyond basic nutritional needs. Components found in functional foods can include dietary fibre, omega-3 fatty acids, antioxidants and plant sterols. These foods can help to increase satiety and thermogenesis, and could potentially support weight loss and maintenance. Many functional foods have been examined in isolation, and with conflicting results.
However, there is no known investigation into the impact of low-energy dense diets in combination with functional foods on weight maintenance, inflammatory markers and cardiovascular risk factors. Researchers designed a study to explore the effect of this combined intervention.
A 3 month randomised control trial was conducted. 90 participants who had been on a previous weight loss diet took part. Inclusion criteria included a desire to maintain weight, a recent weight loss of 7-11kg and age over 20 years. Exclusion criteria included a desire to lose more weight, corticosteroid use, lipid-lowering drug use and poor adherence to the diet.
Participants were randomised to one of 3 groups. The control diet was a diet with a specific calorie amount based on the participant’s body weight. Macronutrient ratio for control was 50% carbohydrate, 25% fat and 15% protein.
The low-energy-dense diet (LD) had calories based on the participant’s body weight, but the diet also used low-energy-dense foods such as broths and soups. Macronutrient ratio for the LD group was 60% carbohydrate, 25% fat and 15% protein.
The third group, low-energy-dense plus functional foods (FF) combined the approach of the LD group with an emphasis on functional foods. Functional foods included green tea, soy, fish, high-fibre foods and almonds. The FF group had the same macronutrient ratio as the LD group.
All of the groups received detailed dietary advice, meal planning and recipe information by a dietitian. Fasting blood glucose, serum insulin, lipid profiles, inflammatory markers, adiponectin, blood pressure and anthropometric measurements were assessed at baseline and at 3 months.
The FF group had a number of statistically significant results compared to LD and control groups. In terms of weight maintenance, the weight, waist measurement and BMI were significantly improved in the FF group compared to the other groups.
There was also significant improvements for the FF group in terms of inflammatory markers and cardiovascular disease risk factors. Blood pressure, malondialdehyde, C-reactive protein, tumour necrosis factor, total cholesterol, LDL cholesterol, triglycerides and fasting blood glucose all improved significantly compared to the other groups.
The researchers concluded that the study demonstrated benefits of a low-energy-dense diet with functional foods. Evidence supported improvements in weight-loss maintenance, inflammation and multiple cardiovascular disease risk factors.
Izadi, V., Haghighatdoost, F., Moosavian, P. and Azadbakht, L., 2018. Effect of Low-Energy-Dense Diet Rich in Multiple Functional Foods on Weight-Loss Maintenance, Inflammation, and Cardiovascular Risk Factors: A Randomized Controlled Trial. Journal of the American College of Nutrition, pp.1-7.