The percentage of people (both adults and children) who are overweight or obese is increasing. This can not be explained by genetics, as the percentage of people who are overweight or obese would remain similar from year to year. The increase must be due either to people eating more or having a lower level of physical activity than previously, or to a combination of these. In other words, people are eating more energy than their bodies are using up.

People, in general, are less physically active than they would have been 20 years ago. For example, children watch lots of TV and play computer games, instead of more active forms of play. Parents take them to school by car, as it is often not safe for them to walk or cycle. Many adults have less physically active jobs than in previous years. Although some are physically active in their leisure time, many are not.

Studies of energy intake suggest that this is reducing rather than increasing over time.

In order to put on weight, individuals do not need to take in much more energy than their bodies use up. One kilogram of fat contains 9,000 kcal. One chocolate confectionery bar, for example, contains about 300 kcal.  Thus, an individual would only need to eat 30 bars that are extra to their energy requirements, in order to put on 1kg of fat. For example, a man weighing, say, 70 kg  (11st) when aged 20 years, if he were to consume one chocolate bar per fortnight that is extra to his energy requirements, would be likely to weigh about 92kg (14st 7lbs) by the time he is 45 years old.

Individuals could avoid putting on weight by doing more physical activity. The additional activity required is not that great. A 10 minute walk every day, for example, would use up enough energy to prevent the increase in body weight described in the example above.  Regrettably, some people have a 10 minute walk once a fortnight and a chocolate bar every day!

In conclusion, there is no excuse for people to become overweight or obese. Prevention is better (and easier) than cure.