Altered body weight associated with substance abuse: a look beyond food intake

Abstract

Background: Substance abuse can cause a range of harmful secondary health consequences, including body weight changes. These remain poorly understood but can lead to metabolic disorders including obesity and diabetes. Energy balance is a function of the equation: energy balance = energy intake – energy expenditure; an imbalance to this equation results in body weight changes. Currently, in the clinical setting, changes to food intake (energy intake) are considered as the primary mediator of body weight changes related to substance abuse, reflected in the current treatment focus on nutritional intervention. The influence of substance abuse on energy expenditure receives less attention. The aim of this think-piece is to consider potential causes of body weight changes during active substance abuse and abstinence, by focussing on the components of the energy balance equation. Methods: We discuss both human and animal studies on the effects of substance abuse on energy balance, with particular focus on animal models utilising pair-feeding, which enable investigation of energy balance whilst controlling for the effects of altered food intake. Results: We demonstrate that whilst some drugs of abuse affect food intake, this effect is inconsistent. Furthermore, body weight changes do not match food intake changes. Conclusion: We provide evidence that drugs of abuse can affect both energy intake and energy expenditure; contributing to the observed body weight changes. This think-piece highlights that treatment strategies for body weight changes related to substance abuse cannot focus solely on nutritional interventions, but should consider the impact of broader disruptions to energy balance.