Formula or meal replacement diets (e.g. Slimfast, Lighter Life)
At the heart of formula diets are meal replacement products which usually come in the form of milkshakes, soups, snacks or ready meals. Most are made from sugar and milk and contain a bulking agent (e.g. plant fibre or gum). By law meal replacement products must provide the recommended amount of nutrients required for good health (providing at least 25% protein and 23 vitamins and minerals). When used properly meal replacement diets can be effective as they provide fewer calories than the person requires to maintain their body weight. However meal replacement diets do not teach people how to make healthy food choices. The food choices available to people who use meal replacements are more limited and this lack of variety may cause them to stop using them after a short period of time. While meal replacements are nutritionally balanced, there is also evidence to suggest that our bodies are better able to make use of the vitamins and minerals found in food rather than those found in fortified foods. There are also few large-scale, long term trials testing the efficacy of meal replacements in “real life” situations.