Exercise associated with reduced levels of fat in the liver and abdomen

A couple of months ago I wrote a blog which reviewed the evidence which suggests that exercise is not particularly effective for weight loss, and why this might be. That is not to say, however, that exercise is a fruitless endeavour. It is linked, for instance, with improved measures of health as well as reduced risk of chronic disease and death. Just last month I wrote about a study which found that exercise, while it did not promote weight loss in obese children and adolescents, it did lead to improvements in fat levels in the liver, insulin levels and insulin sensitivity. Fitness levels improved too.

This last study supports the idea that being ‘fat’ is not a barrier to being ‘fit’. It’s not necessarily a barrier to good health either.

With this in mind, I was interested to read about a recent study which assessed the relationship between health measures and levels of fitness and activity in men [1]. In this study, men were assessed according to the following criteria:

Fat – waist circumference of 100 cm or more
Slim – waist circumference of 90 cm or less

Fit – fitness as assessed by maximal oxygen consumption (VO2 max) greater than average for age
Unfit – fitness as assessed by maximal oxygen consumption (VO2 max) lower than average for age

Active ” engaging in at least 60 minutes of vigorous activity each week
Inactive ” no history of regular moderate or vigorous activity in the last two years

Measures used to assess health included overall fat levels, as well as levels of fat in the liver and ‘visceral fat’ (fat in and around the organs in the abdomen associated with a heightened risk of conditions such as cardiovascular disease and type 2 diabetes).

In slim individuals, being fit was associated with significantly reduced levels of internal fat (compared to being unfit).

In ‘fat’ individuals, being fit was associated with significantly lower levels of liver fat and visceral fat.

Total levels of fat were the same between fit and unfit groups.

This study is ‘observational’ (or ‘epidemiological’) in nature, which means it looked at associations between things, but cannot prove that the two are ‘causally’ connected. However, the results of this study do support the notion that regular activity might not lead to overall reduction in fat levels, but on the other hand may help reduce visceral and liver fat levels, which is likely to have important benefits for long term health. We also have evidence (including the study linked to above) that taking exercise can reduce fat levels in the liver, which points to a genuine role for exercise in reducing visceral fat and the conditions it is associated with it.

In short, the research lends support to the idea that it is possible to be fat and fit (and healthy). It also suggests that while exercise might not be a particularly effective way of losing weight or fat generally, it promotes fat loss from the places in the body where it might be doing the most damage.

References:

1. O’Donovan G, et al. Fat distribution in men of different waist girth, fitness level and exercise habit. International Journal of Obesity 15 September 2009 [epub ahead of print publication]