Debunking the myth of “detox”
Excessive dietary intake and a lack of energy expenditure from physical activity result in a positive energy balance, contributing to weight gain and weight-related comorbidities (Khawandanah and Tewfik., 2016). After Christmas time, a season of rest and indulgence, many embark on restrictive patterns of eating with the hope of a quick and easy solution to weight loss. These short-term diets, often referred to as ‘fad diets’ are marketing myths that promise a multitude of health benefits, such as improved digestion, rapid weight loss and an increase in energy, and emphasise the need to ‘detoxify’ (British Dietetic Association (BDA)., 2019). However, these diets lack any clinical and robust scientific evidence to support their health claims and can bring adverse side effects to physical and mental health (Khawandanah and Tewfik., 2016; Tahreem et al., 2022).
One such popular diet is a ‘detox diet’, a dieting strategy that often restricts whole food groups, promotes the consumption of a liquid-based diet composed of fruit or vegetable juices, detox supplements, and in some instances, supports a period of fasting (BDA., 2019; Carrotte et al., 2015). Other variations of a detox diet encourage the consumption of ‘detox teas’, ‘liver tonics’ or ‘purified water’, liquid concoctions containing all natural or organic ingredients that are commercially advertised as enhancing the ‘cleansing’ abilities of excretory organs, such as the liver and kidneys (Tahreem et al., 2022).
However, the human body has its own natural detoxification abilities that are highly efficient in removing toxins and dismiss the need for dietary detoxification strategies (Tahreem et al., 2022). Whilst organs such as the skin and those of the gastrointestinal tract play a role in the detoxification process, the primary organs responsible are the liver and those of the renal tract (Kieffer et al., 2016). Exogenous and endogenous compounds, such as alcohol, bile pigments, metabolic by-products and xenobiotic drugs, are filtered from the bloodstream by the liver via a two-stage detoxification process that metabolises and conjugates these compounds into less biologically active forms ready for removal via excretory pathways (Cline., 2015; Ozougwu., 2017). To date, studies looking at the effects of detox diets on human health have failed to show an improvement in detoxification processes or identify any mechanism of action for how toxin elimination is enhanced via these diets (Tahreem et al., 2022).
Any positive effects one might feel shortly after undertaking a detox diet are not because of toxin elimination, but instead are likely to come from increasing fruit and vegetable consumption, drinking more water and consuming less refined sugar (BDA., 2019). However, whilst increasing fruit and vegetable intake brings a multitude of health benefits, consuming large volumes of these foods, particularly in the form of juices, can result in a severe caloric deficit that may give rise to instabilities in blood glucose levels, cravings for high sugar foods and lead to bingeing behaviours in a bid to restore energy balance (BDA., 2019; British Heart Foundation., 2020; Hart., 2018). Furthermore, severe caloric restriction has been shown to increase neuropeptide expression in the hypothalamus, resulting in the activation of energy conservation mechanisms, such as metabolic rate suppression and appetite stimulation (Tahreem et al., 2022; Sainsbury and Zhang., 2010).
Caloric restriction is a reoccurring theme in detox diets and one which is often responsible for the rapid, yet unsustainable, weight loss reported. However, rapid weight loss is usually the result of restricted carbohydrate intake, which subsequently leads to lower glycogen and water stores, and long-term, is associated with an increased risk of ketosis, which can have adverse side-effects for many, as well as an increased risk of mortality (Burkitt., 2020). Restrictive dietary patterns can also cause fatigue, weakness, poor recovery from exercise, gastrointestinal distress, increased cortisol levels and imbalances in gut microbial composition and diversity (Carrotte et al., 2015; Khawandanah and Tewfik., 2016; Leeming et al., 2019).
Diet is the primary modifiable factor that can influence the composition of the gut microbiota; the more diversity in the diet, the higher the capability of the gut microbiota in contributing to health (Heiman and Greenway., 2016). Gut microbial stability is influenced heavily by nutrient quantity and quality, and whilst day-to-day variations in diet are not enough to induce noticeable changes in gut microbial composition, habitual dietary patterns play a bigger role (Leeming et al., 2019). As such, constant, repetitive cycles of restrictive dieting have the capability to dysregulate the gut microbiota, reducing richness and levels of beneficial bacteria, such as bifidobacteria (Heiman and Greenway., 2016; Leeming et al., 2019), which has the potential to give rise to ill health (Chan et al., 2013).
The takeaway message
Detox diets are marketing myths that make exaggerated health claims and lack clinical, robust scientific evidence to warrant their use. Often restrictive, detox diets can have various detrimental effects on health, including the gut microbiota, especially when a restrictive dietary pattern is sustained over long periods of time. The human body is capable of detoxifying and eliminating unwanted substances and by-products, even during periods of over-indulgence, dismissing any need for a special detoxification diet or program. Maintaining a balanced and diverse diet is the best way to create sustainable dietary patterns and support all aspects of health and wellbeing.
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