Low fat diets were reviewed by Clifton in a meta-analysis of 13 studies that contained 1,728 individuals. Comparing a low-fat diet to a control diet, the average weight loss is 5.4 kg at 12 months. He stated that a low fat diet has been beneficial in reducing diabetes and high blood presser for up to 3 years in the research reviewed.
Clifton explained that low-calorie diets usually limit intake to 1100-1600 kcal per day. One kcal is equal to 1 calorie as typically discussed in layman’s terms. The author described this diet to have slightly better results to that of a low-fat diet, however the difference in outcome is very small. Clifton expressed that a low-calorie diet combined with moderate fat intake has proven superior results when compared to the low-fat diet. The most common form of this diet is achieved through meal replacements whereby one or two meals per day is replaced with a low-calorie drink and can result in an 8.6% reduction in weight within 12 months. According to Clifton, those on carbohydrate-restricted diets typically feel satisfied longer on this diet because of the increased amount of protein. The success of this diet is attributed to the reduction in appetite. He stated that dieters using this method tend to lose more weight than those on low-fat diets when evaluated after 6 months, but after 12 months the difference is no longer obvious.