The effect of alcohol on body composition

Is cortisol involved in the alcohol-related fat mass impairment? A longitudinal clinical study

AIMS

Subjects with chronic alcohol abuse can present several metabolic and nutritional alterations. The hypothalamic-pituitary-adrenal (HPA) axis may play a role in these nutritional and metabolic disorders. The goal of this study was to investigate if there is any relationship between HP-hormones and metabolic and nutritional parameters in alcoholic subjects.

METHODS

Sixteen alcoholics were considered before and after 3 months of total alcohol abstinence. HP-related hormones were determined. Nutritional and metabolic parameters were assessed by dual-energy X-ray absorptiometry (DXA) and indirect calorimetry.

RESULTS

At baseline, a significant negative correlation was found between fat mass (FM) and cortisol (r = -0.54, P = 0.03). During abstinence, a significant increase of both body mass index (BMI) (P < 0.0001) and FM (P < 0.0001) was found at 12 weeks compared to baseline. A significant decrease of both plasma cortisol (P = 0.044) and aldosterone (P = 0.023) was found at 12 weeks compared to baseline. At 12 weeks, the significant correlation between cortisol and FM disappeared.

CONCLUSIONS

A higher HPA-axis activation-reflected by higher cortisol levels-was associated with a lower FM in alcoholics. Conversely, during total abstinence a reduced HPA-axis activity can play a role in the parallel nutritional recovery. The present results suggest a role of the HPA axis throughout cortisol both in the etiology of the alcohol-related nutritional alterations and in their recovery after a period of total alcohol abstinence.

Is alcohol consumption a risk factor for weight gain and obesity?

Alcohol represents an important source of energy. Despite its comparatively high energy content of 7.1 g/kcal, it is still controversial whether moderate amounts of alcohol represent a risk factor for weight gain and obesity. Epidemiologic data showed a positive, negative, or no relationship between alcohol intake and body weight. Despite the difficulty in assessing alcohol intake as well as controlling for different confounders of the energy-balance equation, the conflicting epidemiologic data can be explained in most instances. Every component of the energy-balance equation is affected by the ingestion of alcohol. Moderate amounts of alcohol enhance energy intake due to the caloric content of the alcohol as well as its appetite-enhancing effects. Alcohol-induced thermogenesis is approximately 20% in healthy nonalcoholic subjects, i.e., moderate alcohol consumers, which is higher than for other energy substrates but considerably lower than in heavy alcohol consumers. This would suggest that a major fraction of the alcohol energy represents a navailable energy source for ATP synthesis in moderate non-daily alcohol consumers. Experimental evidence from several metabolic studies showed a suppression of lipid oxidation by alcohol and thus the enhancement of a positive fat balance. The nonoxidized fat is preferentially deposited in the abdominal area. The experimental metabolic evidence suggests that the consumption of moderate amounts of alcohol has to be accounted for in the energy-balance equation and may represent a risk factor for the development of a positive energy balance and thus weight gain. In the heavy alcohol consumer and eventually also in daily moderate alcohol consumers, a larger fraction of the alcohol energy might not be an available source of energy due to the induction of the microsomal ethanol-oxidizing system (MEOS). Experimental data in combination with epidemiologic findings suggest that alcohol energy counts more in moderate nondaily alcohol consumers than in some moderate daily and all heavy consumers. Accordingly the question is not "Whether alcohol calories do count" but "How much do alcohol calories count?". There seems to be a large individual variability according to the absolute amount of alcohol consumed, the drinking frequency as well as genetic factors. Presently it can be said that alcohol calories count more in moderate nondaily consumers than in daily (heavy) consumers. Further, they count more in combination with a high-fat diet and in overweight and obese subjects.

Nutritional effects of alcoholism

Alcohol is the most frequently used drug worldwide and remains a socially acceptable hepatotoxin. Although the toxic effects of alcohol on various organs (liver, pancreas, heart, and intestine) are well recognized, the role of alcohol in overall energy and protein metabolism is less well understood. In particular, the efficiency of alcohol as a source of calories and as a substrate for energy production appears to be influenced by the amount of both alcohol and fat consumption as well as by gender. The relationship between alcohol intake and body weight is complex, but it is a clinical dilemma with important nutritional implications for weight management in addition to specific organ toxicity.