William RevilleThe most important thing you can do for good health is to get aerobically fit, writes Prof. William Reville
Obesity is a huge problem worldwide and Ireland is no exception. Worryingly, the obesity problem is not confined to the adult populationand childhood obesity in Ireland has been described as a pandemic.
The roots of obesity are complex and dealing effectively with the problem will not be easy. The complexity of the problem is illustrated, for example, by the fact that recent research has correlated the number of hours worked by mothers outside the family home with the incidence of overweight children in their families.
We eat in order to derive energy from the food to power our various bodily activities, to supply us with the necessary biochemical building blocks to renew our bodily structures and to supply us with various essential vitamins and minerals.
The energy content of the food is measured in calories. If we ingest more calories than we burn off in activities, the excess calories are stored by the body as fat. If we consistently ingest more calories than we burn off, we will become overweight and, eventually, obese.
The most common way to categorise body weight is in terms of body mass index (BMI). Your BMI is calculated by dividing your height in kgs by the square of your height in meters. A BMI under 18.5 is categorised as underweight, 18.5 to 24.9 is normal, 25 to 29.9 is overweight, 30 to 34.9 is grade 1 obese, 35 to 39.9 is grade 2 obese and a BMI over 40 is grade 3 or ‘morbidly’ obese.
Heart disease
Obesity is very bad for your health causing a myriad of problems, including type 2 diabetes, heart disease and a shortening of life expectancy. Obesity can shorten life expectancy in adults over 40 years of age by seven years. Obesity in children causes musculoskeletal problems, signs of incipient diabetes, high cholesterol, breathing problems, low self-esteem and depression.
The 2011 National Adult Nutrition Survey showed that 26% of men and 21% of women in Ireland are obese. It is predicted that by 2025, about 50% of men and over 33% of women will be obese.
Ireland is fifth among 27 EU countries for childhood obesity. The 2011 National Longitudinal Study of Children showed that 19% of nine-year-olds are overweight and a further seven per cent are obese. Some 19% of boys and 18% of girls from professional households are obese, and 29% of boys and 38% of girls from semi- and unskilled backgrounds are obese.
Adult obesity is costing the State over €1 billion per annum and this figure will rise enormously unless childhood obesity is effectively tackled.
The solution to the obesity problem is simple in principle: eat fewer calories and take more physical exercise. However, in practice obesity is a complex problem that is difficult to deal with. Sustainable weight reduction in adults who are obese is difficult to achieve, but the prospects of achieving sustainable weight reduction and improved health in children are much better with the right programme.
The complexity of the obesity problem goes far beyond the ingestion of too many calories and involves factors such as exercise, hunger and satiety centres in the brain, genetics and socioeconomics. Although not commonly appreciated, the best predictor of whether you will develop an overweight problem is the weight of your parents. If your parents are/were lean, then you are also very likely to be lean yourself.
Almost 80% of the variation in fatness in the population is accounted for by inherited factors.
Complexity
A further illustration of the complexity of the obesity problem is recent research showing an inverse relationship between the number of family meals eaten per week with overweight children up to the age of seven years. The modern trend of mothers working outside the home makes it more difficult to prepare family meals.
Other research has shown that children of mothers who work more hours outside the home per week are more likely to be overweight than the children of mothers who work fewer hours outside the home, particularly mothers of higher socioeconomic status. (Both studies quoted by G. Osei-Assibey in ‘The Influence of the Food Environment on Overweight and Obesity in Young Children’, British Medical Journal OPEN, 2012.)
It is popular to demonise fast food and sugary drinks as the major contributors to obesity. However, all categories of food contribute – big dinners and lunches, over indulgence in alcohol, cakes and confectionery, etc.
All the various factors that make obesity such a complex problem must be taken into account in order to devise a comprehensive strategy to tackle the epidemic of obesity effectively.
The complexity of obesity is well explained by Professor Mike Gibney, director of The Institute of Food and Health, UCD, in his book Something to Chew On: Challenging Controversies in Food and Health (UCD Press, 2012).
Modest exercise
Anyway, easy or not, at the end of the day, the solution to being overweight must be to eat a healthy diet, modest in calories, and to take plenty of aerobic exercise. Choosing a healthy diet and a healthy lifestyle is easy, contrary to what many people think.
It can be summed up as: “Eat a wide variety of whole foods in moderation, mostly plants, and take plenty of aerobic exercise.”
Aerobic exercise is the exercise of your heart and lungs and you can do it by walking, jogging, running, swimming, cycling, etc. If you decide to exercise by walking, a brisk three-mile/4.8 km walk per day, done in 45 mins, five days a week will keep you fit. Of course if you are unfit to begin with, you should gradually work up to this level over say eight weeks.
In my opinion, the single most important thing you can do for good health is to get aerobically fit.
Some people are naturally a bit chunky and find it hard consistently to achieve a BMI in the normal range. Don’t worry if you are fit but a little bit overweight. Overweight but fit beats lean but unfit.
Developing any new habit requires effort. Many overweight people who decide to cut down on their intake of calories scare themselves by vividly imagining how hard it will be to develop new modest eating habits.
But it isn’t really too hard after the first couple of days – your appetite tends to accommodate to the smaller amounts of food.
Don’t torture yourself with fearful anticipation. Relax. Remember the advice given by Henry Ford: “If you think it’s hard or you think it’s easy, you’re right.”