Low carbohydrate diets (e.g. Atkins, Scarsdale diet, Hollywood diet)
Low carbohydrate diets increased in popularity in the early 2000s with the rediscovery of the Atkins diet as an effective way of losing weight. Low carbohydrate diets are based on the premise that a diet very low in carbohydrate leads to a reduction in the body’s insulin production, resulting in fat and protein (muscle) stores being used as the body’s main energy source.
The ultimate aim of low carbohydrate diets is to force the body to use fat as its main energy source. When this happens a person produces ketones (a by product which is generated when fatty acids are broken down for energy) to fuel parts of the body that cannot use fat as an energy source. During this period a person is said to be in a state of ketosis which is characterised by smelly breath and side-effects such as nausea and fatigue.
While people who go on low carbohydrate diets do lose weight and do so quickly this comes at a price. The majority of weight that is lost comes from loss of water and muscle tissue. As with very low calorie diets this loss of muscle (metabolically active tissue) will lead to a reduction in the number of calories a person needs to maintain their weight.
Followers of low carbohydrate diets also miss out on essential nutrients and vitamins which come from fruit, vegetables and grains. Ketosis can also cause kidney damage in individuals with already established kidney problems.
People on low carbohydrate diets often increase their intake of protein or fat which can lead to other issues. For example, high levels of protein may put an increased strain on the kidneys, risk dehydration and can cause the body to lose calcium, leading to osteoporosis. Higher intake of fat, particularly saturated fat can increase the risk of heart disease in those who follow these diets in the longer term.