Nutrition: People who are apple-shaped are more likely to suffer from heart disease and diabetes than people with bulges elsewhere on the body, a conference in Dublin will be told today.
Dr Sinead McCarthy from the Department of Clinical Medicine at Trinity College, Dublin, is due to discuss the reason for this when she speaks at the annual meeting of The Nutrition Society of Ireland and Great Britain and the UK Association for the Study of Obesity.
She said yesterday that researchers do not yet fully understand why being apple-shaped is associated with increased risk for cardiovascular risk but she said some believe that it may be that a high level of body fat located around the vital organs mean that more fatty acids are released into the blood stream from the liver.
She said that being obese in general brings with it many risks for lifestyle-related diseases such as heart disease, diabetes, hypertension and unhealthy levels of blood lipids, such as cholesterol.
"However, carrying weight around the waistline puts people at much greater risk of developing these conditions," she said.
Until now researchers have concentrated on finding out what causes obesity; now they are turning their attention to the determinants of "central obesity".
Dr McCarthy said that almost all foods we eat are associated with increased risk of obesity and expanding waistlines except for fruit and vegetables and most breakfast cereals.
"What it appears to be is that we are consuming too much of all foods, not just too much of one food. We need to cut down on portions," she said.
She added that apart from energy (calorie) consumption and fat intake being frequently cited as the culprits in the development of obesity other factors may also be important, such as demographic and environmental factors.
"These may contribute to or protect against obesity.
"For example, increasing 'fast food' consumption can lead to increased body weight, while increased education level and higher socio-economic status are associated with a decreased risk for obesity," she said.
While few studies have examined the influences of diet, health and lifestyle factors on central body fat, they have shown that certain environmental factors are associated with this pattern of body fat distribution.
"These include modifiable factors, such as smoking and alcohol use, and non-modifiable factors like age, education and social class.
"While smoking is usually associated with lower body fat, unusually it is associated with a higher waist-to-hip ratio, the usual measure for increased central body fatness. This may add to the cardiovascular risk already associated with smoking," she said.
"Few studies have examined the influence of specific foods, food groups and portion sizes on overweight and obesity. However, current thinking in the USA strongly suggests that expanding food portion sizes may play a major role in the obesity epidemic.
"In Ireland, the North-South Food Consumption Survey, which examined food intake and body fat distribution in almost 1,400 people on the island of Ireland, showed that while no specific food group could be identified as a contributing factor to obesity, the amount of food eaten, as well as the size of the portion eaten, were associated with both obesity and a high waist circumference.
"It is vital that we take on board this evidence for the development of effective weight reducing programmes."