Overweight? Reduce risks by staying fit
WE ARE BOMBARDED nowadays with warnings about the dangers to our health of growing fat but, despite these warnings, obesity statistics continue to worsen.
Many people find it very difficult to lose weight. Well, today I bring good news for people who are struggling unsuccessfully to lose weight but still want to reduce their risk of contracting cardiovascular disease. A new study, by Duck-chul Lee and collaborators (Circulation, vol 124, pp 2483-2490, 2011) reports that keeping fit benefits your cardiovascular health even if you don’t lose weight. This confirms what intuition suggests and is a welcome addition to lifestyle advice, an area bedevilled by slick magic-bullet solutions.
There has been an ongoing debate about the relative risks of being fat but fit. Many studies have correlated people’s fatness and fitness with cardiovascular health, but only at one point in time. However, bodies change with time and this new study followed patients over at least six years and three checkups.
The researchers studied 3,148 adult men and women, mostly in their 40s when the study began, attending the Cooper Clinic in Dallas, Texas. The subjects were normally active but not athletes. When the study began, none of the participants showed indications of heart disease or displayed risk factors such as high blood pressure or high cholesterol.
At the second check-up, two to three years after the first check-up, researchers compared patients’ body fat and aerobic fitness. Most had gained body fat by the second check-up but many had also become fitter (probably heeding advice to take exercise). No patient showed heart-disease risk factors at the second check-up.
The picture changed at the third check-up, several years later. Almost a quarter of the patients had now developed elevated blood pressure, higher cholesterol levels or a condition known as metabolic syndrome. If you display three out of the following five conditions you will be diagnosed with metabolic syndrome: bloated waistline, high blood-fat level, low HDL cholesterol (“good cholesterol”), high blood pressure, high blood sugar.
The patients most likely to develop these health problems were those who both gained fat and lost fitness. They were 70 per cent more likely to develop metabolic syndrome than subjects who had lost fat. Fitness offered protection – a person who improved in fitness and added fat had a 22 per cent risk lower than the person who was at the same time fat and unfit.
It must be emphasised that losing fat in itself also reduced the risk of developing health problems, but very few people in this study lost fat. The overall conclusion of the study is that exercise alone will not erase the health risks of extra body fat, but it may blunt these risks. As Dr Lee says: “Both fitness and fatness matter, separately and together, for heart health.”
The study also showed that all that may be required to protect the heart is to maintain fitness rather than to improve fitness. “So much attention gets focused on weight reduction, but reducing body fat is very difficult for most people. Our study suggests that, in terms of heart health, maintaining your fitness over your lifetime is just as important, and for most people is probably more achievable,” he added.
Official advice on healthy lifestyles is a maelstrom of rapidly changing prescriptions. Fat and sugar are dirty words despite the fact that every membrane in every body cell is made of fat, vitamins A, D, E and K are fat soluble, and your brain depends exclusively on glucose for energy. Some processed foods proudly display the legend “low fat”. The problem, however is that reducing fat also removes flavour and, to compensate for this, calorie rich sugars are added to keep the food palatable – there are no labels on the box about this. Eating low-fat processed foods to reduce weight is not a useful strategy.
The only basic nutritional/lifestyle advice the average person needs to know is simple and based on sound principles: eat a wide variety of foods in moderation, mostly unprocessed and mostly plants, and take plenty of aerobic exercise. Dr Lee’s advice also falls into that simple and sensible category. There is no need to give up on cardiovascular health if you are somewhat overweight – maintaining fitness is still good for the heart
William Reville is an emeritus professor of biochemistry and public awareness of science officer at UCC. understandingscience.ucc.ie