What benefit does exercise have in the fight against worldwide obesity?

What benefit does exercise have in the fight against worldwide obesity?

According to the OECD in 2005 (Appendix 1) America has the highest percentage of obesity at 30.6% with the European countries varying from 22.4% in Slovakia to the lowest in Europe which is Switzerland at 7.7%. Ireland’s rate at that time was 13%. Obesity being defined as a BMI rating of 25 or over.
Exercise has long been advocated to help people to lose weight but is it a cure for obesity or a red herring. In a recent article by Cloud in Time magazine entitled “Why exercise won’t make you thin” he argued that exercise has a very small role to play in losing weight. On the other hand countless research has shown that exercise does indeed help someone to lose weight. I wanted to look at research to see what is the latest findings on the search for a cure for obesity and does exercise play a role in any new strategy being developed.
 

 Exercise and Appetite

Studys shows that a person can lose weight through exercise but why then is it not happening for a lot of the population. Asking an individual to exercise for an hour a day is perhaps too unrealistic for the ordinary person. Even when a person does get that amount of exercise done there is no guarantee that they will lose weight as they might compensate in other ways. In a study called ‘Metabolic and Behavioral Compensatory Responses to Exercise Interventions: Barriers to Weight Loss’ King et al looked at the compensatory responses that are made by people after exercise. They found that partial or complete compensatory responses to exercise can influence the potential success of weight loss. The metabolic responses included a reduced resting metabolic rate, reduced energy cost of activities, and reduced energy costs that comes with weight loss. All these combined could have an effect on a person’s ability to lose weight. The behavioral responses included becoming less active in other times of the day after exercising or feeling that a person was entitled to a treat after exercising and often taking in more kcal than they have burned off.

This does not apply to everyone though and it should be looked at from the individuals point of view. King et al did a study whose purpose was to identify and characterize the individual variability in compensation for exercise-induced changes in energy expenditure (EE).

The study by King et al showed that exercise does  have an effect on the suppression of hunger. The study looked at subjects on a bicycle ergo meter at a low effort of 30 % of vo2 max. After the exercise there was no effect on the ratings of hunger before the lunch time meal. In comparison when asked to exercise at an intensity of 70% this led to a significant suppression of hunger. What about eating habits in the days afterwards ? In the same study they found that during 24 hours of the exercise day after burning either 250kcal or 500 kcal, there was no difference in the amount of food taken in. Also there was no increase in the amount of food taken in the following two days either.

Intensity:

The intensity of exercise does have an effect on appetite what then about the duration?

In 2009 church et al did a controlled study to look at the effects that different durations of exercise would have on weight loss. There were over 400 inactive, obese or overweight postmenopausal put in to different groups. Each group had a set amount of exercise that they
would do each week. The four different times were 194 min, 136 min, 72 min or 0 min (control group) and the exercise was supervised. The women were asked to keep their dietary habits the same and they also had to fill out a monthly health questionnaire. After 6 months the results showed that there was weight loss in each of the 3 groups as predicted.
In the 72 min and 136 min groups the actual weight loss closely matched the predicted weight
loss resulting in no significant compensation. The weight loss in the 136 min group matched very closely. In the 72 min there was slightly more weight loss than predicted.

Importantly though in the 194 min group there was weight loss but it was under half that predicted indicating that there was some compensatory factors counteracting the predicted weight loss. They did however note that a quarter of the people who exercised for more than two hundred minutes per week did lose the predicted amount of weight.  It is worth mentioning though that the all exercise groups had a significant reduction in waist circumference which was independent of changes in weight. They concluded that strategies to identify and treat potential compensators were needed.

Benefits of exercise:

Recent studies again point again to the benefits of exercise. King et al recently supervised an exercise intervention with 58 obese, sedentary and overweight men and women. They took part in a twelve week aerobic study. The participants had to exercise five times per week at 70 % of max heart rate for five times a week and had to burn 500 kcal. Body composition, blood pressure aerobic capacity, blood pressure and psychological effects from exercise were measured at weeks 0 and 12 weeks.

Twenty six of the 58 participants failed to attain the predicted weight loss estimated.
However despite the fact that they did not get the weight loss there were significant other benefits. There was an increase in aerobic capacity, decreased systolic and diastolic blood pressure. They also had a reduction in waist circumference. Further benefits included a reduction in resting heart rate and an improvement in positive mood.
In their study on exercise and brain function Hillman et al  stated that there is converging evidence that physical activity such as weight training and aerobic training can have a positive effect on multiple aspects of brain function and cognition.

 Reasons for obesity:

The obesity epidemic has come about for many different reasons and lack of exercise is only one of them. Wide spread price competition amongst manufacturers of food products has encouraged them to make product sizes larger in a bid to increase sales. Their profits rise in turn with the rise in the product size.(Berry et al, 1983) This obviously increases the amount of kcal that the customer consumes. The same can be said for fast food outlets and restaurants who in a bid to give the customer the best value have also increased their portion size. (Didomenico, 1994) The customer is also looking for better value and will choose the place that they will eat based on the size of the portions. (Carangelo, 1995)
Peoples do not have the ability to judge the amount of food that there are taking in at any one sitting. They view the volumetric size of the food on the plate rather the amount of kcal that is actually on the plate.
Obesity now starts with children and then they carry it with them in to adulthood. Western society has now become more sedentary with children’s leisure time involving more television, computer and video games which means much less exercise. (Anderson and Butcher 2006

Viewpoint:

What role does exercise have to play in the fight against obesity? There has been some confusion about the ability of exercise to help a person to lose weight.
The National Weight Control Registry in the United States keeps data from people who lose weight in the long term. 80% of persons in the registry are women and 20% are men.
The "average" woman is 45 years of age and currently weighs 10st 5lbs, while the "average" man is 49 years of age and currently weighs 13st 8 lbs.  Registry members have lost an average of 4st 10 lbs and kept it off for 5.5 years.  Weight losses have ranged from 2 to 10 stone.
Most reported continuing to maintain a low calorie, low fat diet and doing high levels of activity.
78% eat breakfast every day.  75% weigh themselves at least once a week.  

Losing weight is difficult and no one strategy will work for everybody. The correct portion sizes are an important step and also to be able to recognise what foods are high in kcal. It is not so long ago that the standard size of a bag of crisps in Ireland was 25 grams. That is now up to 40 grams.Peanuts is another example whose potion size has increased by a whopping 50% from 25 grams to 50 grams bags. There is no option but to buy the bigger portion as the smaller one is longer available. In their research “Public opinion and the politics of obesity in Americs” Oliver and Lee looked at how Americans view potential solutions to the obesity problem. They discovered that people mainly accepted responsibility for their own obesity and were not looking for scapegoats. Public opinion had not given any huge support for suggested  policys by the government to help combat obesity. Some of these included snack taxes, improving civil liberyties protection for obese individuals and increasing public spaces for exercise. The most popular policies were one that tackled child obesity. They included regulating television ads that targeted young children as young as six. It is important that there is early intervention to try and stop children growing up in to obese adults. Governments need to play a more active role in educating  people to the different amount of kcals in different foods.  

Education for the individual is important when they are trying to lose weight. Without the knowledge that some people lose weight at different rates because of genetics or compensatory mechanisms it would be easy for the individual to get de-motivated at their perceived slow rate of weight loss. It is also important then the fitness professional is aware of this knowledge and can set goals accordingly for an individual. Exercise should be seen as a very important tool in the fight against obesity but it should not be put forward as the only tool. The benefits of exercise are so many that it cannot be caught up in the blame game for a person’s inability to lose weight or get thin. It was not so long ago that exercise was again used in the fight against cholesterol but in the end a drug solution was found for people who had been exercising but still could not get it down. Perhaps there will be a drug found that will cure obesity but for the moment exercise, behavioural interventions and improved nutrition are still the key players.

Appendix 1
Health Statistics > Obesity (most recent) by country

DEFINITION: Percentage of total population who have a BMI (body mass index) greater than 30 Kg/sq.meters (Data for Australia, Austria and Portugal is from 2002. All other data is from 2003). Obesity rates are defined as the percentage of the population with a Body Mass Index (BMI) over 30. The BMI is a single number that evaluates an individual's weight status in relation to height (weight/height2, with weight in kilograms and height in metres). For Australia, the United Kingdom and the United States, figures are based on health examinations, rather than self-reported information. Obesity estimates derived from health examinations are generally higher and more reliable than those coming from self-reports, because they preclude any misreporting of people's height and weight. However, health examinations are only conducted regularly in a few countries (OECD).

OECD Health Data 2005 via NationMaster
http://www.nationmaster.com/red/graph/hea_obe-health-obesity&b_printable=1
Accessed {13/11/09}

Oliver J, Taeku L. Public Opinion and the Politics of Obesity in America. Journal of Health Politics, Policy & Law [serial online]. October 2005;30(5):923-954. Available from: Research Starters - Sociology, Ipswich, MA. Accessed November 13, 2009.