Research Review: Belly fat – location, location, location

By Helen Kollias

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The fitness industry seems obsessed with belly fat. Nearly every infomercial for fitness equipment or weight loss plans has a picture of some rippling abs. Not glorious glutes or a broad back, but a six-pack.

Researchers are obsessed with belly fat too, but the belly fat they’re interested in is on the inside, around your organs — aka visceral fat.

Way back in 2009, I wrote a research review looking at belly fat. Belly fat is part visceral fat (around the organs) and part subcutaneous (under the skin, which hides your rippling abs).  This week I’ll explain why visceral fat causes health problems.

Visceral fat: The unpinchable fat

We all cringe when we squish our fat between our fingers. It could be fat on your hip, thighs, belly or even on your upper back (when did that happen?), but that isn’t the fat you should be worried about.

While all this fat under your skin (subcutaneous fat) is easy to see, it’s the fat inside your belly that’s the big health problem.

I’m not saying you shouldn’t keep track of your skinfolds, since they’re usually a good indicator of what going on inside, but there are times when skinfolds don’t tell you what’s going on inside your body.

We need some visceral fat to cushion our organs. Otherwise everything would get mashed together and bruised every time you moved around. But as with most things in physiology, we need a happy medium — a bit, but not too much.

Diversity in visceral fat: Abs don’t tell the whole story

Correlations between total body fat and visceral fat range quite a bit.

Lean people have the worst correlations (0.4), which means that having a relatively low body fat doesn’t necessarily mean you have low visceral fat. Body fat and visceral fat in overweight people usually correlate better (0.8). This means if you’re overweight, you’ll have a fair bit of visceral fat.

If you’re lean and sedentary, you may have visceral fat and if you’re overweight and sedentary you almost certainly have too much visceral fat.

It’s always fun to look at exceptions. One exception to the “more body fat equals more visceral fat” rule is sumo wrestlers. Sumo wrestlers eat over 7,000 calories a day, have BMIs over 36 kg/m2 but with very little visceral fat, and by all other medical measures, they’re healthy. Sumo wrestlers give us a big clue (pardon the pun) about how to prevent and reduce visceral fat.

Too much visceral fat: Health consequences

Since getting rid of your visceral fat won’t reveal your six-pack, why should you bother? Well, visceral fat is linked to a laundry list of diseases:

  • Insulin resistance
  • Cardiac dysfunction (left ventricular dysfunction)
  • Hyperglycemia (high blood glucose)
  • Hyperlipidemia (high blood fat)
  • Coronary artery diesel
  • Sleep apnea
  • Diabetes
  • High blood pressure

OK, we can agree that visceral fat is bad, but how much is too much? Well, more than 100 cm2 is definitely too much, since it’s linked to diseases.

How to lose (or gain) visceral fat: Factors in visceral fat accumulation

I’ve been telling you how bad visceral fat is and how you can even be lean and still have visceral fat, so what should you do?

First, become a woman, preferably a pre-menopausal woman.

Yup, being a women means you’ll have less visceral fat, since women have less visceral fat compared to men of the same BMI. This seems to be linked to women having more sex hormone binding globulin (SHBG) and waist-hip ratio. Once women hit menopause, the freebie runs out: they start getting as much visceral fat as men.

For most guys, becoming a woman is out of the question (barring a lot of hormonal and surgical intervention). OK, how about you get younger? As we get older we not only accumulate cats, ties, single socks, and ear hair, but visceral fat too.

How about changing your genetics? Families tend to have the same amount of visceral fat and so far, a mutation in the gene for the beta-3-adrenergic receptor seems to increase visceral fat.

Hmmm, anti-aging and human genetic engineering are a few years off, so what else can we do? Reduce your sugar. Finally, something you have control over. High-sugar diets have been shown to increase visceral fat in people and animals.

Remember the sumo wrestlers with little visceral fat even though they were obese? All the physical activity they do prevents and reduces visceral fat. Great, now you need to wrestle a 300 pound sumo wrestler to keep your visceral fat in check.

SumoWrestler

Well, there might be another option: Weight training.

Research question

Today’s study asks the question: Can you change fat deposition — in particular, deposits of visceral fat — with weight training?

Idoate F, Ibañez J, Gorostiaga EM, García-Unciti M, Martínez-Labari C, Izquierdo M. Weight-loss diet alone or combined with resistance training induces different regional visceral fat changes in obese women. Int J Obes (Lond). 2010 Sep 7. [Epub ahead of print]

Methods

Participants

Most resistance (aka weight training) studies are done on healthy young men in university or college, for a bunch of reasons from “easy to convince to be a part of the study” to “will do muscle biopsy for beer money” to “harder to injure”.

The problems with this: most people are not young men, and many folks who’d get the most benefit from weight training aren’t healthy.

This study, in contrast, used obese women between the ages of 40-60 — precisely the type of folks who should be weight training for improved health and body composition.

The researchers didn’t just look at whether weight training would help these women lose fat, but whether weight training affected where they lost fat.

Diet versus diet + weight training

The researchers randomly split up the women into one of three groups:

Group 1: Control group – this group kept doing what they were doing before.

Group 2: Diet-only group – this group ate 500 calories less a day than before the study, with 55% calories from carbohydrates, 15% from proteins and 30% from fat. The goal was weight loss of 0.5 kg (about 1 pound) a week for the 16 weeks during the study.

Group 3: Diet + weight training – these folks were on the same diet as Group 2, the diet-only group, plus they got to work out. Workouts were whole body workouts twice a week, with at least two days between each workout, for 16 weeks.

Workouts for Group 3

Workouts were done entirely with machines and included three core exercises: leg press, leg extensions, and bench press, plus four of the following:

  • lateral pull down
  • shoulder press
  • abdominal crunch
  • rotary torso
  • back extensions
  • standing leg curl
  • hip adduction
  • hip abduction
  • chest press

During the first half of the study the women used 50-70% of their 1 repetition maximum (the most they could lift) for 10-15 repetitions and 3-4 sets for all the exercises. In the second half of the study they used 70-80% of their 1 repetition maximum for 5-6 repetitions and 3-5 sets.

Plus they did explosive training for leg extensions and bench press. Explosive training used 30-50% of the women’s 1 repetition max, but only 20% range of motion.

To make sure the volunteers were getting the most out of their workouts they were supervised by the researchers and weight was added as the women got stronger.

Results

Weight training and belly fat

After 16 weeks, Group 2 and Group 3 both lost about 7 kg (15.4 lb) of body weight, decreased their waist by nearly 7 cm (2.75 in) and dropped their BMI by over 2 kg/m2. The control group saw no changes in weight, waist girth or BMI.

Great! 16 weeks of working out and there was no difference in results. FAIL!

Well… wait a sec. There were no differences in the traditional, scale-and-tape-measure results, but there were differences in the more high tech measurements.

Since the only way to find out how much visceral fat you have is using a scan (CT or MRI), everybody had an MRI scan to find out how much visceral fat they had (you knew there had to be a reason for the introduction).

Group 3, the dieting weight lifters, lost the most visceral fat between lumbar disks L2-L3 compared to just dieting or doing nothing (control). This lost fat is closer to the liver.

MRI visceral fat Figure 1
Figure 1: MRI scan of a woman before (top panels, a) and after (bottom panels, b) diet and weight lifting for 16 weeks. T12 is thoracic vertebrae 12, L1 is lumbar vertebrae 1 and S1 is sacral vertebrae 1.

Dieters (without exercise) also lost visceral fat but in a different area, L5-S1 (closer to their toes).

No big surprise that the control group didn’t lose visceral fat, since they didn’t have any changes in the other measurements.

Conclusion

In this study, weight training changed where women lost fat while dieting, but not the amount.

Women who weight trained twice a week lost more visceral fat near their liver (L2-L3), compared to just dieting where visceral fat was lower (closer to their toes, L5-S1).

What does this mean for you?

For right now the researchers don’t know if having less visceral fat closer to your liver makes any difference, so you’ll have to wait and see what they figure out in the next few years. Since fat is hormonally active and it’s been known to annoy the neighbours with loud chemical parties, this could be significant.

I have to point out that even though there was no difference in overall weight lost, BMI, or waist girth measurements between the dieters and weight training dieters the exercise program was pretty wimpy: only twice a week; using weights that I figure wouldn’t last for more than an hour per workout, so 2 hours a week of weight training.

While better than nothing, I’d recommend at least 3 whole body workouts a week plus some sort of additional exercise, running, biking, and/or sumo wrestling to get the weekly activity to around 5 hours a week.

Bottom line

Eating 500 calories less a day for 16 weeks will lead to weight loss, reduced BMI, smaller waists, and reduced visceral fat, but adding weight training to the mix can change where you lose the visceral fat.

References

Click here to view the information sources referenced in this article.

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