Scientists are constantly saying that levels of obesity are increasing. What is the reason for this increase?
Obesity is increasing because the amount of energy individuals consume, from the food they eat, is higher than the amount they use up in the daily activities they perform. Body weight is maintained by a simple energy balance between the amount of energy consumed and the amount of energy expended. The national food survey has identified that over the last 25 years the amount of food we consume has decreased. This implies that the levels of obesity are increasing because the amount of physical activity performed is declining. There is also inconclusive evidence to suggest that a high fat, low carbohydrate diet favours the development of obesity. Over the past 5 decades the proportion of energy that is derived from fat has increased, while the proportion of carbohydrates has decreased. Fat has a lower priority to be utilised for energy expenditure than carbohydrate and is more likely to be stored than 'burnt off.' 
Where does the UK stand in the obesity league compared with the rest of the world? 
On a global scale more than 1 billion people are overweight, 300 million of which are obese. Currently the highest levels of obesity exist in the USA where it affects 30.6% of the population. In comparison, 22.4% of the UK's population is reported to be obese. This is the third highest level in the world below the USA and Mexico, and is shortly followed by Australia. Is it true that obese people have a lower metabolic rate and do not actually eat more than those of normal weight? It is not true to say that obese people have a lower metabolic rate. In fact, because obese people have more weight to bear; their energy expenditure will be higher in carrying out the same task as a lean person. Resting metabolic rate is greatly determined by the amount of muscle and fat tissue. The higher stores of fat that obese people have will lead to a higher metabolic rate. The research that was conducted into metabolic rate and possible defects in this being the cause of obesity were abandoned. This is because it became clear obese people frequently under report when recording their diets. In some cases obese people may not eat much more than those of normal weight but their extreme weight gain is a result of physical inactivity. 
Does obesity run in families? 
The levels of obesity have accelerated over a relatively constant gene pool which makes it apparent that an individual's genetic make-up is not enough to be the sole cause of obesity. There is evidence to suggest that there may be a susceptible gene which makes some individuals more prone to the risks of obesity. This must be combined with adverse environmental conditions, such as poor dietary habits and lack of exercise, to cause extreme weight gain. As eating patterns are habitual it is more likely that a child with obese parents will develop obesity. 
Physical activity is often blamed as a factor in obesity. How much activity should we be doing and does exercise help you to lose weight? 
It is recommended that every adult, whether overweight or not, should take part in thirty minutes of moderate intensity physical activity on at least five days per week. Physical activity of moderate intensity is equivalent to a brisk walk and should be enough to raise body temperature, produce a mild sweat, but still remain comfortable. Obese individuals will find it difficult to reach this target so it would be sufficient to begin with a shorter time period and build it up over several weeks. Physical activity by itself will result in moderate weight loss. To achieve the greatest loss in weight it should be accompanied by diet restriction. 