Exercise found to improve ‘fat genes’, but what about its effect on actual fat?

My eye was caught yesterday by this report of a study into the effects of exercise on fat tissue. In the study, 23 overweight and healthy men engaged in a 6-month programme of exercise. The recommendation was for three, 1-hours sessions per week (1 cycling/spinning and 2 aerobics sessions). In the final analysis, the individuals averaged 1.8 sessions per week (108 minutes of exercise a week).

What the study showed was the exercise appeared to change the expression of about a third of the genes in the fat cells, including some that relate to the risk of type 2 diabetes and the development of obesity. The authors of this study also draw our attention to benefits in terms of changes in waist circumference, waist-to-hip ratio, diastolic blood pressure (the lower of the two blood pressure readings), resting heart rate and levels of HDL-cholesterol. All good news, generally speaking.

However, I know from experience that when people adopt what they believe to be healthier behaviours, while they may have the long game in mind they also tend to like to see short-term pay-off too. Feeling like tangible progress is being made is, often, a great motivator for people. Whether we agree with this or not, many overweight individuals see their weight as an important marker of progress. The fact that weight is not mentioned in the report of the research raised a little red flag in my mind. I went to look at the actual paper here. This is Table 1 from the study which details the apparent effects of exercise on a range of body measurements.

Table 1

Here, you will that weight only declined by 1 kg on average (not statistically significant). If the waist circumference fell by 2 cm, that would suggest some fat loss. So, perhaps the group lost fat and gained muscle? Well, if you look at ‘fatness (%)’ in the table you’ll see that it did not change. Overall, the individuals seemed to be no less fat for their efforts.

In short, the results from a weight- and fat-loss perspective were pretty dismal and, for many individuals may have been quite demotivating.

While the results of this experiment on weight and fatness may be surprising to some, they actually reflect a considerable body of evidence which shows pretty much the same thing: aerobic exercises are, by and large, quite ineffective for the purposes of weight loss (though they may, of course, bring lots of other benefits).

I have previously explored why exercise may not deliver on its weight loss promise here. Increasing exercise can cause people to eat more. The problem is that, in general terms, exercise does not burn tons of calories (unless we’re doing heroic amounts of it). It doesn’t usually take much additional eating to wipe out any calorie deficit induced through exercise.

Also, although exercise is said to boost the metabolism, it appears this may not reflect reality for some people. Part of the post I link to above draws on studies highlighted by Jeff Volek and Stephen Phinney in their book ‘The Art and Science of Low-Carbohydrate Performance’. It shows that in overweight individuals, exercise can actually have a suppressant effect on the metabolism.


1. Rönn T, et al. A Six Months Exercise Intervention Influences the Genome-wide DNA Methylation Pattern in Human Adipose Tissue. PLoS Genetics. Epub 27 June 2013

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6 Responses to Exercise found to improve ‘fat genes’, but what about its effect on actual fat?

  1. Eddie Mitchell 10 July 2013 at 11:49 am #

    Have you thought of the benefits to our almost bankrupt old age pension scheme John ? Set in place a gruelling exercise regime for the obese middle aged guy, and secure a good deal with the COOP funeral service and huge savings could be made. Of course if you really want to help the patient, give him a lowcarb diet plan, around fifty carbs per day is about right. Give him recipe cards showing him the wonderful meals that can be made by even the most un-skilled cooks. Because the high fat meals are more satiating many lowcarbers consume less calories and don’t feel hungry because they are not on a roller coaster of high and low blood glucose numbers brought about by plasma insulin spikes etc.

    As weight is lost, which is typical, introduce some modest exercise such as walking and swimming. Instead of increasing heart attack risks, the patient should notice Trigs plummeting and increased HDL cholesterol. Many report a reduction in blood pressure and slower heart rate. Reduction of fatty liver, a massive reduction of risks associated with type two diabetes and other metabolic diseases. The list of benefits is long. But what does the fat guy get ? A handful of pills, a lecture that he should lose weight and a photocopy of an out of date diet plan, which is useless, dangerous and scientifically illiterate.

    What’s wrong with lowcarbing ? Of course the diabetes and weight loss industries lose out big time. Big pharma and junk food companies take a big hit. The NHS, DUK, ADA, and many Doctors and dieticians look complete idiots, for promoting the high carb low fat diet of death for so long. How can a small (but growing) group of healthcare professionals and trouble making amateur bloggers, know better than the fonts of all knowledge. Meanwhile the fonts oversee out of control type two diabetes and obesity epidemics, they point their fingers at the fat guy, he always was an easy target, blame the fat guy, he brought it on himself.

    Regards Eddie

  2. David 11 July 2013 at 6:25 am #

    “around fifty carbs per day is about right”
    Fifty big carbs or fifty little carbs?

  3. Nigel Kinbrum 11 July 2013 at 9:08 am #

    Hi John,

    Exercise is good, but too much exercise can be counter-productive. See http://suppversity.blogspot.co.uk/2013/07/the-glucose-repartitioning-effects-of.html

    Also, do you have any comments on the adverse effect of VLC diets on serum NEFAs in people with excessive visceral adiposity?

    Cheers, Nige

  4. PhilT 11 July 2013 at 11:22 am #

    Good spot. Non-significant increase in % body fat. LOL.

    @David – grams of UK carbohydrate presumably ?

  5. RadiantLux 12 July 2013 at 8:00 pm #

    it looks to me like this study chose chronic cardio for the exercise. One hour per session? It is counter productive! Did they check fat / muscle composition? I would like to see the same study using interval training and strength training using body composition as a measurement.


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