What does the passage mainly talk about?

A report by the Royal College of Physicians stated that a third of Britons are overweight. About five percent of children weigh too much, and are likely to stay that way for life. In the mid-twenties age group the proportion of overweight people has risen to a third, and in the middle-aged population, half are overweight.
    The safest way to lose weight is to eat cereals, bread, fruit and vegetables, and cut down on fatty meats, butter and sweet foods. Fat diets do far more harm than good; machines that vibrate muscles have not been proved useful; saunas merely remove a little body water, and health farms serve as expensive holidays.
    Exercise is most important to health, the report emphasizes, though it doesn’t necessarily reduce weight, it maintains the correct proportion of body fat to body muscle. And it isn’t only for the young; from middle age a minimum of 20 minutes of gentle physical jerks should be practised three times a week.
    The report advocates several public health [11C] measures to combat the high prevalence of overweight problem in this country. They include an increase of tax on alcohol to reduce its increasing and dangerously fattening consumption, and [13B]the provision of more sports facilities by local authorities. Britain’s doctors, the report concludes, must learn to be more sympathetic and specific in their advice to the overweight, encouraging a change in eating habits on a long-term basis, and taking into account the many, often complex reasons why overweight people are overweight.