A meal replacement diet literally involves main meals being replaced with low-kilojoule powdered shakes and snack bars. The aim is to reduce the overall energy intake, thus aiding weight-loss. There is evidence to suggest that a meal replacements are an effective way to lose weight. However, it is not a long-term fix and more general knowledge is required before undertaking such a diet program.
How Does Meal Replacement Work?
Anything that is labelled as a meal replacement is a kilojoule-controlled product. Such products are designed to facilitate rapid weight-loss whilst conserving lean body mass (the muscles and organs). Usually, meal replacement formulas are mainly protein based and contain little carbohydrates. They are also supplemented with vitamins and minerals.
Meal replacements were originally developed to replace all daily meals, as part of a “very low energy diet”. Essentially, the overall function of meal replacements is to cover the body’s need for protein in as few kilojoules as possible. The average person requires around 8,700 kilojoules per day to maintain their current body weight. On a low energy diet, only 1,800 to 2,500 kilojoules are consumed.
Meal Replacement and Weight-Loss
When the total kilojoule intake is restricted, the fuel stores in the muscles (glycogen) run low. Once this happens, the body then uses the fat stores for fuel. This is known as ketosis.
All meals are usually replaced for six weeks. A small bowl of vegetables and a small amount of oil are also included, in order to keep up nutrient intake and gall bladder function. Essentially, this is a form of fasting, therefore medical supervision is required. This is done through frequent monitoring by a GP and dietitian or specialist nurse.
Not Everyone Should Try Meal Replacement
Normally, low-energy diets are recommended to adults who are obese and need to lose a substantial amount of weight in a short period of time. They are not suitable for children, pregnant women, people with eating disorders and those who take medication that is affected by weight-loss (insulin is an example).
Not a Long-Term Solution
Although a meal replacement diet can be useful for some people in the short-term, sticking to a regular eating pattern is the best way to maintain weight in the long-term. Meal replacements aren’t a quick fix. To effectively achieve sustained weight-loss, lifestyle, social factors as well as eating and exercise habits all need to be addressed.