There is a widespread assumption that cocaine use suppresses one\u2019s appetite and thereby contributes to weight loss, and that during withdrawal, the \u201crebound\u201d from this effect leads to rapid weight gain. However, new research from the University of Cambridge has provided evidence against this assumption, and while the overall effect is essentially the same, the mechanism by which it occurs is quite different. The findings have notable consequences for how we think about cocaine withdrawal, as well as providing evidence that the general problems with regulating impulsivity in cocaine-dependent individuals also have an impact on their diet. Dr. Karen Ersche of the Behavioural and Clinical Neuroscience Institute at the University of Cambridge said: \u201cOur findings challenge the widely held assumptions that cocaine use leads to weight loss through appetite suppression. Rather, they suggest a profound metabolic alteration that needs to be taken into account during treatment.\u201d Previous Research Aside from the well-documented link between cocaine cessation and rapid weight gain, studies on animals have revealed that while cocaine use leads to an initial delay in the intake of food, there is a compensatory eating period afterward. This finding challenged the general consensus that cocaine suppressed appetites as did research on humans, which indicated that cocaine users actually consume more fatty foods without experiencing the increase in weight you might expect. These findings paved the way for the new study, which aimed to identify the reason for this discrepancy. The Study Led by Dr. Ersche, the new research looked at 65 men, about half of them meeting the diagnostic criteria for cocaine dependence, and aimed to determine their eating behaviors, food intake, the concentration of a protein called leptin in their plasma and their body composition. The measurements of eating behaviors and food intake were dependent on direct surveys of the participants themselves, whereas more direct scientific methods were used to measure leptin concentrations and the proportion of fat mass, lean mass and bone mineral density. What Did They Find? As might be expected from the impulsive nature of cocaine users, the men who were dependent on the drug showed less restraint in their diets, too. They were more likely to eat uncontrollably than the non-dependent group, and exerted less restraint over their diets to control their weight, indicating that users were not especially concerned with their level of food intake or body image. A direct result of this difference in eating habits is that cocaine-dependent men consumed more fats and carbohydrates than the non-dependent group. These differences were significant, although cocaine-dependent men were more likely to skip breakfast and consumed less sugar than the healthy men. They considered the potential impact of tobacco smoking or of other drug consumption on the results, but when they were controlled for, the results didn\u2019t change. Similarly, although the self-reported nature of these elements could have led to some problems with reporting, previous research has shown that non-treatment seeking users are generally honest when reporting personal information. Said Dr. Ersche: \u201cWe were surprised how little body fat the cocaine users had in light of their reported consumption of fatty food. It seems that regular cocaine abuse directly interferes with metabolic processes and thereby reduces body fat. This imbalance between fat intake and fat storage may also explain why these individuals gain so much weight when they stop using cocaine.\u201d Plasma leptin, one of the key measures the researchers looked at, regulates the relationship between appetite and the expenditure of energy. This basically maintains the body\u2019s balance of energy consumption to expenditure, and is therefore central to weight management. The cocaine-dependent group members had less leptin in their bloodstreams (correlated to how long they\u2019d been taking the drug), and when combined with the high-fat diet of the cocaine group, should have been indicative of a notable increase in weight. However, the results from the study clearly showed that the cocaine-dependent individuals had less body mass overall than the non-dependent group. More specifically, the cocaine-dependent participants had a significantly lower amount of fat mass when compared to fat-free mass than the group of ordinary men. So this means that despite the fact that the cocaine users ate more food which should contribute to notable weight gain, they didn\u2019t gain weight and actually ended up with less fat than those not taking the drug. The results therefore indicate that cocaine does reduce weight gain, and specifically fat storage, but that this effect has nothing to do with the suppression of appetite. People Don\u2019t Take Cocaine to Lose Weight The researchers also asked the participants about their reasons for taking the drug, with the majority responding that they did so because they \u201cliked the effects\u201d of cocaine. In fact, out of all of the reasons which were provided (including boredom, increasing sexual pleasure and an open-ended \u201cother\u201d category), none of the users said that they took the drug to reduce their appetite or lose weight. Despite the fact that the effect does seem to have some genuine biological mechanism, cocaine does not appear to be used as a weight-loss aid. Conclusion: Consequences for Withdrawal The research has many implications for how we understand the link between cocaine use and body weight, but it mainly impacts on how we help users through withdrawal. It implies that the \u201cweight gain\u201d diet of fats and carbohydrates actually persists throughout cocaine addiction, and that the drug alters the body\u2019s metabolic pathways to prevent this diet from having the effect it should. This means that when people stop taking the drug, their diet doesn\u2019t suddenly change, it probably continues as usual but without the cocaine it leads to weight gain. Although the dietary advice often offered to ex-cocaine users is still of value, what is needed is a healthier change in diet and not a maintenance of their ordinary diet.