The paper, “Alcohol consumption and body weight: a systematic review”, analaysed the effects of alcohol consumption on body weight across 31 studies published between 1984 and 2010.
Epidemiological studies selected included 14 cross-sectional studies, 14 prospective cohort studies and four intervention trials.
The starting point for the study is the fact that energy content in 1g of alcohol is 29kj or 7.1kcal, which means that alcohol consumption can lead to weight gain.
But academics C Sayon-Orea, M.A Martinez-Gonzalez and M Bes-Rastrollo, concluded that overall results of studies were contradictory, and did not demonstrate a clear trend.
For instance, a large US cross-sectional survey between 1997 and 2001, ‘The National Health and Nutrition Examination Survey’, found that odds of being obese and overweight in those who had never smoked was significantly higher for heavy drinkers (4+ drinks/day).
However, “light to moderate drinking (1-2 drinks/day was associated with significantly lower odds of overweight and obesity compared to non-drinkers,” the academics concluded.
And they reported that a Danish study of 42,696 adults, Halkjear et al. (2006), reported negative associations for both sexes who consumed one glass of wine a week to one glass per day, with the smallest waist circumference gain for those who drank slightly less than one glass of wine per day.
Most of the cross-sectional studies found a positive association between alcohol consumption and body weight or measures of abdominal adiposity, said the authors, especially in heavy or binge drinkers.
But moderate consumption was "either negatively associated or not associated with body weight or abdominal adiposity".
”Moreover, a positive association was seen more frequently in men than in women,” the academics said, a finding they concluded could be due to habitual drink choice and likely higher alcohol intake amongst men.
Prospective study data was also contradictory, with some studies finding that sex was a significant determinant of results, while others found that both male and female heavy drinkers showed the greatest weight gain or had the highest incidences of obesity.
Moreover, when some studies analysed each type of alcoholic beverage separately, they found – specifically for wine drinkers – only negative associations regarding weight gain and adiposity, while spirit drinkers registered positive associations.
“While this might be explained by a healthier overall pattern of wine drinkers, it has also been reported that some components of red wine have the ability to aromatase expression of adipose tissue, which is accompanied by a decrease in adipocyte size and body weight,” said the academics.
Another potential causal mechanism that could lead to lower weight gain with red wine is the presence of the phytoalexin resveratrol, the academics noted, which reportedly inhibits de novo lipogenesis and inhibits lipogenic gene expression.
Assessing the overall results of studies, Sayon-Orea, Martinez-Gonzalez and Bes-Rastrollo wrote:“The overall results do not conclusively confirm a positive association between alcohol consumption and weight gain.
“However, positive findings between alcohol intake and weight gain have been reported, mainly from studies with data on higher levels of drinking.”
They added: “Moreover, light-to-moderate alcohol intake, especially wine intake, may be more likely to protect against weight gain, whereas consumption of spirits have been positively associated with weight gain.”
Future research should assess the specific roles of various alcoholic beverages, according to the authors – specific given the anti-inflammatory properties of polyphenolic components in red wine – while also taking consumption patterns into account.
The authors added that an important limitation of some studies was self-reported weight, height and waist circumference, with participants tending to underestimate their weight and overestimate their height.
Source: Nutrition Reviews, August 2011(Vol. 69(8):419–431)
“Alcohol consumption and body weight: a systematic review”
Authors: C Sayon-Orea, M.A Martinez-Gonzalez and M Bes-Rastrollo.