Dr. Jeffrey Horowitz is a professor of kinesiology at the University of Michigan’s school of kinesiology. “Our research showed that people who exercised regularly and for long periods of time showed positive effects on their adipose tissue when overweight or obese,” he says. “Not only is it a means of burning calories, but regular exercise also appears to change your fat tissue in such a way that you can store it more healthily if and when you experience any weight gain – and almost everyone does as they get older. ”
The study examined and compared abdominal fat samples from two groups of adults who looked the same weight to the naked eye, especially in the central area. But one group exercised four times a week and the other did not. “The athletes had more ‘good fat’,” says Horowitz. “It appears that their efforts have increased their ability to store fat under the skin – or subcutaneously – rather than around their organs.”
Can you tell how much visceral fat you have? And does this encouraging new research mean we can stuff ourselves with fancy chips as long as we rock out at the gym? This is what the experts say.
What is bad belly fat?
Visceral fat is stored in the omentum, an apron-like patch of tissue that lies beneath our abdominal muscles and covers our intestines. The omentum becomes harder and thicker as it fills with fat. “We used to think of this fat as just ’empty storage,’ but newer studies have shown that this type of fat is a biologically active organ that secretes harmful hormones,” says King.
A growing number of studies have linked visceral fat to a surprisingly wide variety of diseases. “Visceral fat interferes with the functions of the kidneys and liver,” says King. “It contributes to diabetes and circulatory diseases, as well as high cholesterol.” Visceral fat produces proteins called cytokines that can cause inflammation, a risk factor for heart disease and other chronic conditions.
A study reported in Harvard Health which looked at women between the ages of 45 and 79, concluded that those with the largest waists (and those with the largest waists in relation to their hip size) had more than double the risk of developing heart disease. Belly fat also increases the risk of asthma, dementia, breast and colon cancer.
What is ‘good’ belly fat?
“We need to reshape the way we look at all fat,” says Horowitz. “Some subcutaneous fat is good for you. It protects your body and serves as an energy source. Only 20 percent of healthy adipose tissue actually consists of fat cells, the rest consists of collagen with a lower inflammatory profile. This tissue is also full of capillaries that remove waste products from the body.”
However, Horowitz makes it clear that this is only the case with subcutaneous fat that develops under the skin, and not around the organs.
How can you tell what type of fat you have?
“You can’t tell where your fat is by looking in the mirror,” says Horowitz. “It’s actually quite difficult to decipher this in an imaging study.” Despite this, a quick Google will bring up a series of ads for readily available scans that promise to show how much visceral fat you have.
For example, Dexa scans were created to measure bone density, but some practitioners are now marketing them as an expensive private way to look at fat composition. “It’s not that easy to use a Dexa scan to tell you exactly where your fat is,” says King. “The most accurate way to do this is through a whole-body CT scan or MRI, but these are expensive and most doctors do not want to perform them for this purpose.”
The best way to monitor your belly fat, says King, is to keep an eye on your waist circumference. “If you feel your jeans are tight, it indicates that you are gaining weight in the mid-range,” he says. For a more detailed analysis, measure your waist circumference by wrapping a measuring tape around your waist, just above your hip bones. For women, 35 inches or more means you are at risk for health problems due to visceral fat. For men, the number is 40 inches or more.
Then measure your height and divide it by your waist circumference. A ratio greater than 0.5 to 0.59 indicates that you have excess fat around your abdomen. And if your ratio is 0.6 or higher, your risk is even greater.
“For a layman, this is a pretty good way to determine if you’re at risk,” says King. “It doesn’t necessarily tell you whether the fat is subcutaneous or visceral, but it’s quite likely that a large waist circumference is an indication that you have harmful belly fat.”
The role of exercise in reducing belly fat
“It’s clear that a physically active lifestyle can lead to healthier fat tissue,” says Jeffrey Horowitz. The good news is that while we tend to put on visceral fat more quickly than subcutaneous fat, research suggests that we also start to lose it quickly when we address our lifestyle – especially through exercise.
Are there specific exercises that can help? Spot exercises, such as sit-ups, can tighten the abdominal muscles, but do not reach the visceral fat (and liposuction for cosmetic fat removal does not reach the abdominal wall). “It’s unfortunately not possible to target one area or type of fat,” says King. “To lose weight you simply need an energy deficit, which means you consume more calories than you take in.”
Both King and Horowitz suggest that endurance training – such as brisk walking, jogging, cycling or rowing – is likely to be more effective than resistance training such as weights, which burn fewer calories. A 2021 meta-study published in the journal Obesity indicated that there was no significant difference between regular exercise and intense exercise, so there’s no need to go crazy.
An important point to note: exercise alone will not be enough in a global weight loss program. The 2021 Obesity Research also shows that exercise is limited to a total weight loss of 1.5 to 3.5 kg. That is why a healthy diet remains important for the overall maintenance of a healthy weight and healthy fat composition.
Ultimately, James King welcomes Horowitz’s study in Michigan, and while he points out some limitations – that the study was ‘cross-sectional’, rather than ’cause and effect’, meaning it did not show that visceral fat was lost in real time subcutaneous fat changed – he finds it encouraging news. “Anything that contributes to the ‘exercise is medicine’ narrative has to be a good thing,” says King. “It shows another benefit of being active.”
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