“I can’t help being fat, it’s in my genes!’ We hear this statement quite often but is it the whole truth?  Obesity is a major global health problem. In 2005, it was estimated that at least 400 million adults were obese (BMI > 30) world-wide. By 2015, it is estimated that the number will increase to about 700 million. Genome-wide studies have identified 12 alleles (an allele is a locus on a chromosome where the DNA is different) that are associated with increased BMI. Does the possession of one or more of these alleles sentence you to a life of obesity? Or could you influence this genetic predisposition to increased obesity risk by lifestyle changes?

Researchers from Cambridge University genotyped the 12 loci in a population-based sample of 20,430 adults from the European Prospective Investigation of Cancer (EPIC)-Norfolk cohort and assessed the influence of a physically active lifestyle on the genetic predisposition to obesity in these individuals (PLoS Med 7(8): e1000332. doi:10.1371/journal.pmed.1000332). The study showed that, in a 1.70 metre tall person, every additional BMI-increasing allele was associated with an increase in BMI equivalent to 445 gm in body weight. In physically inactive individuals, the increase was 592 gm per allele. In physically active individuals, the increase was 36% lower at 379 gm per allele. In physically inactive individuals, possession of one of these obesity-susceptibility alleles increases the obesity risk by 15.8%. However, in physically active individuals the risk is 40% less at 9.5%.

While possession of the wrong genes can predispose an individual to weight gain, the trigger for weight gain is not purely genetic. We have to provide that trigger in the form of inappropriate lifestyle choices. Eating more than we need, eating foods that are high in fat and sugars, lack of physical activity due to increasingly sedentary lifestyles are all triggers to the worldwide obesity epidemic. Becoming obese not only affects self esteem and image, it also brings with it a slew of health problems such as heart disease, hypertension, diabetes, steatohepatitis, joint problems and cancer.

The next time you are about to blame your weight gain on mother nature, perhaps you might want to think again!

A 9^th December Reuter article headline “Tax sugary drinks to fight the flab, says expert” caught my eye. In the article Barry Popkin, Professor of Nutrition at University of North Carolina, suggested that sugary drinks should be taxed like cigarettes in order to reduce the numbers drinking them. Depending on the country, 10 – 25% of all calories are consumed in the form of sugary or calorie-rich beverages. In USA, replacing sugary drinks with water could cut 300 – 600 calories a day from the diet of an average American. At present 1 in 3 American adults is obese which predisposes them to diabetes mellitus. In the next 25 years, the number of diabetes cases in USA is forecast to triple to 44 million and the yearly cost of caring for them will rise to $336 billion. This is just one condition related to obesity.

Nowadays, it is not uncommon to see young children drinking sugary drinks at McDonald’s. Does this predispose them to obesity? Researchers from the Pennsylvania State University studied the possible relevance of beverage intake at age 5 to adiposity and weight status across childhood and adolescence in 170 non-Hispanic white girls (Am J Clin Nutr 2009; 90: 935 – 942). These girls were assessed biennially from age 5 to 15 for beverage intake (milk, fruit juice and sweetened beverages) and energy intake. The percentage body fat, waist circumference and BMI were measured. The 5 year olds were categorized as consuming <1, ≥ 1 but < 2 or ≥ 2 servings of sweetened beverages per day. The study found that sweetened beverage intake at age 5 was positively associated with adiposity from age 5 to 15 years. The consumption of ≥ 2 servings per day was associated with a higher percentage of body fat, waist circumference and weight status at these ages. There was no association with milk or fruit juice intake.

Sugary drinks, such as Coca Cola, epitomise the American way of life and they are craved by many, young and old, throughout the world. Regular consumption brings with it the problem of increased calorie intake on top of a regular diet which contributes to the development of obesity for many. Recently, researchers from Harvard University published their forecast of the effects of obesity and smoking on life expectancy in USA. The researchers concluded that if past obesity trends continue unchecked, the negative effects of increasing BMI will overwhelm the positive effects of the decline in smoking in the population (N Engl J Med 2009; 361: 2252 -2260).

Obesity is a global health issue which is not only confined to affluent, developed societies. Taxing sugary drinks may help to tackle the issue of obesity; however, it is unlikely to solve the problem. To make a significant dent in the obesity problem, society as a whole has to demand tougher measures. For one, perhaps society should consider imposing a minimum age limit on the purchase of sugary drinks which would at least help us fight the childhood obesity epidemic. Will this fly? Most likely not.

There has been a steady increase in overweight and obese people worldwide. In 1976, 14.5% of American adults were overweight and obese. By 2003 – 2004, the percentage had increased by almost 5 times to 66.3%! Does weight gain during early adulthood and mid-life adversely impact upon one’s healthy survival beyond 70 years of age?

Researchers from the Harvard School of Public Health and University of Warwick tested their hypothesis that mid-life adiposity is associated with a reduced probability of maintaining an optimal health status among those who survive to 70 or older by using the data in the Nurses’ Health Study (BMJ 2009; 339: b3796). This study involved 121,700 female registered nurses aged 30 – 55 living in one of 11 US states who responded to a questionnaire about history of disease and demographic and lifestyle characteristics every 2 years from 1976 to 2000. Those nurses who survived to age 70 or older and as of age 70 were free from 11 major chronic diseases (cancer, diabetes, myocardial infarction (MI), congestive heart failure, coronary artery bypass surgery (CABG), stroke, kidney failure, chronic pulmonary disease, Parkinson’s disease, multiple sclerosis and amyotrophic lateral sclerosis), had no major cognitive function impairment, had no major physical functions limitation and had good mental health were termed “healthy survivors”. Nurses who survived to 70 but did not meet these 4 criteria are termed “usual survivors”. There were only 1686 (9.9%) “healthy survivors”.

At baseline, the healthy survivors were healthier, had received more education, a lower prevalence of cigarette smoking and somewhat better diet. In addition, when compared to usual survivors, they were less likely, at baseline, to have overall or central obesity and tended to gain less weight since age 18. The most common chronic diseases were cancer, coronary heart disease (MI and CABG) and diabetes. Increasing BMI at baseline was associated with reduced odds of healthy survival. Every one unit increase of BMI was associated with a 12% reduction of the odds of healthy survival. Compared to stable weight, weight gain since age 18 was significantly associated with reduced odds of healthy survival. For every 1 kg increase of weight since age 18, the odds of healthy survival were decreased by 4 – 6%. Even among non-smokers, compared to lean women (BMI 18.5 – 22.9), women with a BMI of 30 at baseline had 73% lower odds of healthy survival. Compared to women who maintained a stable weight, women who gained 20 kg had 84% lower odds of healthy survival. A higher BMI at 18 also adversely affected the chances of healthy survival. Relative to women with a BMI of 18.5 – 22.9 at age 18, those with a BMI of 23.0 – 24.9 had 15% lower odds of healthy survival and for those with a BMI ≥ 25, it was 33% lower.

The above study would imply that there is no safe period for becoming overweight in our lifetime. It behoves every one of us to stay vigilant about our weight and try to stay lean if we want to enjoy healthy survival at 70 and beyond.