Findings debunk claims that low carbohydrate diets result in more weight loss
Low carbohydrate diets result in similar weight losses when compared to recommended balanced diets, according to researchers at Stellenbosch University.
The study, published in the online journal PLOS ONE, pooled the results of 19 clinical trials that met specific criteria and measured weight loss and heart disease risk factors such as blood cholesterol levels. This study included 3 209 overweight and obese participants, some with diabetes.
“This systematic review shows that when the amount of energy consumed by people following the low carbohydrate and balanced diets was similar, there was no difference in weight loss after three to six months and after one to two years in those with and without diabetes”, says lead researcher, Dr Celeste Naudé from the Centre for Evidence-based Health Care at Stellenbosch University’s Faculty of Medicine and Health Sciences.
Low carbohydrate diets reduce energy (kilojoule) intake by avoiding starchy foods (such as oats, bread, rice, potatoes, beans and lentils), and by restricting certain vegetables (such as butternut and carrots) and most fruits. The diets recommend people eat as much fat as they want, especially animal fats, or as much protein as they like, or both. When following extreme forms of these diets, around 80 percent of a person’s energy can come from fat alone. High fat and protein intake is known to reduce hunger leading to less food intake and thus less energy intake.
By contrast, a balanced weight loss diet reduces energy intake by guiding healthy food choices and decreasing portion sizes, while keeping the carbohydrate, protein and fat within the recommended ranges of intake. A balanced diet includes plenty of vegetables and fruit, with intake of unrefined carbohydrates (such as oats, brown rice, whole grains, sweet potato and beans) and emphasises vegetable and fish fats and oils instead of animal fats, as well as lean proteins (such as lean meats, fish and seafood, poultry and lower fat dairy). Large studies over long time periods show that this diet pattern ensures that all nutrient requirements are met and reduces the risk of chronic lifestyle diseases.
“Weight loss occurs, irrespective of whether the diet is low carbohydrate or balanced, and there is little or no difference in weight loss or changes in heart disease risk factors and diabetes markers up to two years of follow-up”, said Professor Jimmy Volmink, co-author and Dean of the Faculty.
Dr Vash Mungal-Singh, chief executive officer of the Heart and Stroke Foundation South Africa says: "This study clears up the misperception that low carbohydrate diets are more effective for weight loss. It is important to note that heart disease and stroke develop over many years of exposure to unhealthy diets and other risk factors such as smoking, obesity, high alcohol intake and inactivity. The follow-up of these weight loss trials is no longer than two years, which is too short to provide an adequate picture of the long term risk of following a low carbohydrate diet.”
The full article is available from PLOS ONE.
Click here for a summary of the article.
For more information contact:
Dr Celeste Naudé
Centre for Evidence-based Health Care, Faculty of Medicine and Health Sciences, Stellenbosch University
Tel: +27 (0)21 938 9886
Faculty of Medicine and Health Sciences, Stellenbosch University
Tel: +27 (0)21 938 9505
Heart and Stroke Foundation South Africa
Tel: +27 (0)21 447 6268
Association for Dietetics in South Africa
Tel: +27 (0)82 376 4446
Prof Nelia Steyn
Nutrition Society of South Africa
Prof Krisela Steyn
Chronic Disease Initiative for Africa
Tel: +27 (0)21 406 6802
Prof Edelweiss Wentzel-Viljoen
Professional Board for Dietetics and Nutrition of the HPCSA
Mobile: +27 (0)18 299 2467
For more about Stellenbosch University, refer to www.sun.ac.za.
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