Dr Kevin McCarroll
Are you overweight? It may be a sobering thought, but in fact about 80% of Irish adults aged over 50 are overweight or obese according to the TILDA study of ageing. What’s even more alarming is that approximately 20% of Irish children and adolescents also fall into this category.
Overall, the rate of obesity in Ireland has trebled in men and doubled in women in the last three decades placing us nearly at the top of the obesity table in the EU. This rising trend is set to continue with the WHO predicting that 89% of men and 85% of Irish women will be overweight or obese by 2030.
Obesity is one of the leading preventable causes of death worldwide and on average reduces life expectancy by six to seven years. Extra weight via mechanical factors contibutes to osteoarthritis, high blood pressure, sleep apnea and reduced exercise tolerance.
Fat
An increased amount of fat tissue contributes to high blood triglyceride and cholesterol levels, fatty liver disease, insulin resistance (causing diabetes) and chronic low grade inflammation. In fact, excess fat is the major factor in about 70% of cases of type II diabetes. It also appears to increase the risk of several cancers including bowel, oesophagus, breast and ovaries.
The average body contains about 30 billion fat cells, though this number may be twice as high in those who are overweight or obese. In fact, the number of fat cells may peak in early adolescence, but remains fairly constant in adulthood even after weight loss. This may in part explain why younger adults who are overweight are more likely to remain so in later life.
Fatty tissue is metabolically active with endocrine, metabolic and immunological functions. Fats cells secrete up to 50 adipokines (chemicals) which have diverse roles including mediating inflammation. Fat which is distributed viscerally (around the gut) is considered to be more harmful and is associated with much greater production of inflammatory chemicals. Production of oestrogen in fat cells may account for the greater risk of breast cancer and abdominal obesity (contributing to chronic acid reflux) and likely increases the risk of oesophageal cancer.
Muscle mass
So what constitutes being overweight? If you have a body mass index (BMI) between 25-30 you are generally considered overweight, though it is sometimes accounted for by differences in muscle mass in those who have normal body fat and are healthy.
A BMI of 30 or above is consistent with obesity which usually equates for most adults to being overweight by more than about two stone. In older adults, abdominal obesity (which carries a greater risk) is not reflected well by BMI and is better correlated with waist measurements or waist hip ratio. As a guide, waist circumference should not exceed 37 inches for men and 32 inches for women.
The vast majority of cases of obesity and weight excess are caused by increased energy intake in the diet and /or reduced energy expenditure. In practise, it is usually due to a combination of both of these factors. Indeed, in Ireland the majority of adults and children do not engage in the recommended level of physical activity.
Furthermore, eating habits that include greater consumption of fast foods, high energy sugary drinks, saturated fats and refined carbohydrates have been linked to weight gain. Sugary drinks are less filling than food and can be consumed quicker resulting in higher caloric intake. Several environmental factors also influence eating habits. For example, studies show that families who eat together consume more healthy foods whereas eating out and watching TV is associated with a higher intake of fat. Furthermore, in children the number of hours spent watching TV correlates with consumption of the most advertised goods, including sweets, sweetened cereals and drinks, and salty snacks.
In most cases, a core factor in losing or maintaining weight loss is doing more vigorous physical activity (about 60 minutes per day). In addition, it’s important to note that from a health perspective several studies have shown beneficial effects of exercise on cardio-metabolic risk factors even in the absence of any weight loss.
Portion sizes
Where relevant, limiting fast foods and TV time, using appropriate portion sizes and consuming recommended portions of fruit and vegetables should reduce energy intake. Weighing yourself once a week and tracking your weight has been shown to be a major factor in both achieving and maintaining weight loss. In practice, most weight loss programmes usually achieve and maintain a drop in weight of about 10%.
It is clear that a multi-faceted approach to tackling the ‘preventable’ public health problem of obesity needs to address several environmental and social factors. In particular, studies show there is a lack is awareness of what constitutes an unhealthy weight and proper diet in a high proportion of adults.
As a simple starting point, a knowledge of what our weight is and should be, will help us focus on keeping an eye on it, as well as watching our diet and making sure to do regular exercise.
Dr Kevin McCarroll is a consultant physician in geriatric medicine in St James’ Hospital, Dublin.