Detox diets and cleanses, which are often celebrity endorsed, promise a significant weight loss in a short space of time. But is this quick fix better than going to a gym and putting in the hard work?
"Simply put: No! Instead of looking at extremely low-calorie consumption you need to be looking at the importance of the how the brain regulates body weight," says Dr Jason McKeown, visiting scholar in Neuroscience at the Centre for Brain and Cognition, University of California, San Diego.
"Most traditional methods of dieting and detoxing (including dieting pills, juice detoxes, cabbage soup, no carbs, etc) are not enough, and when people stop dieting, this will all almost certainly lead to significant 'bounce back' (with some regaining all of the weight they have just lost).
"Ultimately, your brain automatically controls what weight we need to be, so doing an intense detox for a few weeks almost never leads to any meaningful weight loss in the long run."
During a detox diet, whole food groups are cut out while caffeine, alcohol, sugar and processed foods are restricted. Most of the weight lost will be water, stored glycogen and waste products, and most if not all of the weight will be regained once returning to 'normal' eating habits.
Is detox necessary?
The scientific evidence suggests that detox diets and cleanses are neither necessary nor valuable. The body is perfectly capable of eliminating unwanted contaminants; the liver, kidneys and digestive system, and enzymes in cells, are continuously breaking down toxins and internal waste.
"The human body has a robust cleansing system to help us to get rid of waste products of metabolism and toxins," explains GP Dr Tuya Chuluuntulga from the CosmeSurge Clinic in Harley Street.
"When we chew food, amylase enzymes produced by saliva help to break down carbohydrate. Proteases break down protein in the stomach and small intestine. Lipases break down fat and oil in the small intestine. These digestive enzymes break down nutrients into small soluble molecules that can be absorbed. A variety of waste products are filtered by the liver. The kidneys remove waste and toxins from the body. The colon reabsorbs fluids and gets rid of food left over after the nutrients are absorbed from it and other waste. We don't need to detox because it doesn't offer any clinically proven health benefits."
"Not only are detox diets not good for people with certain medical conditions like cancer, diabetes, immunocompromised patients, etc, they could be harmful," Chuluuntulga continues. "There is no research providing evidence they improve health outcomes such as blood pressure, or cholesterol, or have a long-lasting effect on weight."
Furthermore, some detox diets are extreme and if followed for long periods can cause nutritional deficiencies, lack of energy, fatigue, and an increase in food cravings because food groups have been restricted. In some cases, they trigger unhealthy eating patterns and behaviours.
Embarking on a new diet, even a detox, forces you to evaluate your diet, while also being more motivated to increase the amount of fruit and vegetables eaten, to drink more water and to cut down on junk food, alcohol and caffeine. These are, however, long-term efforts and should become part of a healthy eating regime. They are not a quick fix to weight loss.
"There are many healthier ways to achieve target weight by focusing and adopting a healthy lifestyle," encourages Chuluuntulga. "It is important to nourish and maintain the body's robust self-cleansing system with a balanced healthy diet, regular exercise, adequate fluid intake, sufficient sleep and a positive mindset.
A more effective alternative
"Taking a long-term approach that allows your brain to adjust to your weight loss is always my number one recommendation," advises McKeown.
"Maintaining a slow and healthy weight loss, through moderate changes in lifestyle, better nutrition choices, and modest physical activity like a brisk walk a few times a week, is much more sustainable and therefore less likely to lead to rebound weight gain."
Detox diets claim to help eliminate toxins from the body and aid weight loss while also promoting health and well-being, but there is no clinical evidence to support such claims.
While they might help in the short term, the reality is that any weight lost during detox is likely to be regained once returning to normal eating habits. Instead, doctors and nutritionists recommend a long-term approach to weight loss which allows the body and brain to adjust to a healthier lifestyle - including a healthy diet rich in fruit and vegetables with regular exercise.