May 2016 Issue
Overweight/Obesity: Fighting Belly Fat
By Dave Yeager
Vol. 18 No. 5 P. 12
Regular exercise and overall weight loss can help reduce cardiovascular risks.
It's not inevitable—age-related weight gain, that is. While people often find it challenging to keep the pounds off as they grow older, maintaining a healthy weight—especially around their midsection—has more to do with lifestyle than the date on their birth certificate.
"One of the main strategies for keeping fat off, especially visceral fat, which is really the most worrisome, is keeping up a high level of physical activity," says Kerry J. Stewart, EdD, director of clinical/research exercise physiology and a professor of medicine in the cardiology division of Johns Hopkins Medicine in Baltimore. "Part of the reason why people accumulate abdominal fat, as they get older, is likely related to the fact that they are probably being less active."
Stewart has done numerous studies on the effects of exercise, and he says three factors strongly influence whether a person develops fat-related health complications. The first is where the fat accumulates: the legs and buttocks vs around the middle (ie, the classic pear vs apple shape). Fat deposits around the middle correlate with a higher risk of health complications.1
The second factor is the amount of visceral fat a person has. Unlike subcutaneous fat, which accumulates underneath the skin, visceral fat typically forms around the body's organs, many of which are around the waist. As subcutaneous fat amasses, visceral fat tends to develop as well. Stewart says visceral fat can become a ready source of energy for the liver to convert into metabolic processes, increasing the risk of cardiovascular disease (CVD).
"The reason for that is fat is not an inert substance. We used to think of fat as simple storage for excess calories, which the body can draw upon as needed," Stewart says. "We now know that fat, particularly belly fat and visceral fat, is a source of inflammatory substances, such as C-reactive proteins and interleukin-6—what we call cytokines. And those substances float around the blood stream and begin attacking the blood vessels, particularly the blood vessels in the heart, which can make people more susceptible to clots."
In addition to CVD, Stewart says visceral fat can lead to metabolic syndrome, a collection of risk factors that include elevated blood pressure, increased triglycerides, higher LDL cholesterol, and greater diabetes risk. Unfortunately, while subcutaneous fat is easy to spot and measure, visceral fat is not. Stewart says visceral fat usually is detected by a CT or magnetic resonance imaging scan. He says that although visceral fat is more difficult to detect, people aren't likely to have one type without the other.
Move It or …
A third important risk factor of fat-related health issues is lack of physical activity. Stewart says, as activity increases, risk factors decrease, likely because regular physical activity helps people burn calories and lose weight.2 Although diet and exercise don't always cause big changes in overall weight, he says body composition is what matters; just as people gain visceral fat with subcutaneous fat, they also lose visceral fat with subcutaneous fat. In one of Stewart's studies, increases in lean muscle mass and decreases in overall fat were associated with improvements in systolic blood pressure, diastolic blood pressure, total cholesterol, very low LDL, triglycerides, and insulin sensitivity.2
When it comes to reducing visceral fat, Stewart says exercise is the key. He says regular physical activity tends to burn visceral fat before other fat deposits. A good rule of thumb, he adds, is that a reduction in waist circumference typically indicates a loss of visceral fat.
"If your pants are looser, you're being successful," Stewart says. "If the weight comes off around the middle, you're likely to be burning visceral fat."
Current guidelines recommend 150 minutes of moderate intensity exercise per week (approximately 30 minutes per day, five days per week) for adults older than 18, and include at least two days of resistance/strength training.3 But paying attention to exercise is only part of the battle, says Joan Salge Blake, MS, RD, LDN, a clinical associate professor at Boston University's Sargent College of Health and Rehabilitation Sciences and a spokesperson for the Academy of Nutrition and Dietetics (the Academy). She says modern lifestyles have robbed people of natural calorie-burning opportunities.
"It's important to move more throughout the day. Unfortunately, technology has made our lives highly sedentary. Even simple things that we did years ago, we no longer do," Salge Blake says. "For example, people used to have to walk to the copy room to get a printout. Now, printers are so cheap that many people have their own printer in their office. That may not seem like a lot of movement, but it's many steps that have been eliminated. Or people often take the elevator instead of the stairs. Or they order groceries online instead of going to the store. For a lot of people, going to the gym is just offsetting the activity that they've lost. We've forgotten how mobile we used to be."
Finding ways to move more is a message many people have heard but aren't acting on, Salge Blake says. More than two-thirds of Americans are considered overweight or obese.4 So getting that message across can have a significant effect on public health, she says.
"A 3% to 5% weight loss can still make a difference in people's outcomes for disease prevention," says Isabel Maples, MEd, RD, a spokesperson for the Academy. She adds that small changes such as parking in the farthest spot in the parking lot, taking a couple of laps around the mall before you shop, or bringing multiple loads of laundry downstairs, rather than a large single load, all can add up.
For best results, increased activity should be accompanied by dietary changes.5 Although many types of diets can help reduce weight, waist circumference, and increase lean muscle, one of Stewart's studies found that a low-carbohydrate diet is more effective than a low-fat diet.5 However, people lost weight and improved body composition on both types of diets.5 Other studies have found that simply restricting calories and increasing activity leads to weight loss and improved body composition.6
Of course, losing weight is one thing, but keeping it off is another. To maintain weight loss, Salge Blake recommends that people focus on foods that make them feel full longer, such as whole fruits, whole vegetables, and whole grains. She also recommends that individuals consume refined grains and drink juices in moderation. In addition to increasing physical activity, cutting calories, and focusing on whole foods, Salge Blake says people need to change how they relate to food.
"If people ate only when they were hungry, most dietitians would be out of business," Salge Blake says. "We eat for so many reasons other than hunger. We may be sad, depressed, anxious, bored, or tired. So changing the behaviors and how we deal with our emotions [means] people need to find life outside the kitchen. When you try to comfort yourself or relieve stress or anxiety with food, you're going to have two problems: the original problem and the extra calories you just consumed in an attempt to relieve your stress. People need to retrain their habits and find other ways to release that emotion, such as with physical activity."
Another effective way to change eating behaviors is to make incremental changes, Maples says. When working with clients and patients, Maples recommends finding out what food issues they have and choosing foods they're willing to give up vs foods they'll never give up. In this way, dietitians can help people get the most nutrition with the least number of calories and develop eating strategies clients will follow.
"Some changes can make a big impact. If somebody is eating [calorie-dense] snacks during the day or starving themselves all day and then consuming 500 calories while they're cooking dinner, they need to be mindful of those extra calories," Maples says. "Then, small changes can make a difference, especially if they're changes that people don't really care about. For example, somebody may want to eat fried chicken, but they don't mind giving up M&M's. You need to work with the client to figure out where they don't mind cutting calories. Look at their diet history and their weight history to see if there have been changes and weight gain, and then try to identify a few spots where they can start. Little changes can add up."
— Dave Yeager is editor of Radiology Today.
1. Waist size matters: how abdominal fat increases disease risk. Harvard T.H. Chan School of Public Health website. http://www.hsph.harvard.edu/obesity-prevention-source/obesity-definition/abdominal-obesity/. Accessed March 23, 2016.
2. Stewart KJ, Bacher AC, Turner K. Exercise and risk factors associated with metabolic syndrome in older adults. Am J Prev Med. 2005;28(1):9-18.
3. Physical activity basics: how much physical activity do you need? Centers for Disease Control and Prevention website. http://www.cdc.gov/physicalactivity/basics/index.htm. Updated June 4, 2015. Accessed March 1, 2016.
4. Obesity and overweight. Centers for Disease Control and Prevention website. http://www.cdc.gov/nchs/fastats/obesity-overweight.htm. Updated February 25, 2016. Accessed March 1, 2016.
5. Losing belly fat, whether from a low-carb or a low-fat diet, helps improve blood vessel function. Johns Hopkins Medicine website. http://www.hopkinsmedicine.org/news/
helps_improve_blood_vessel_function. Published March 13, 2012. Accessed March 1, 2016.