Drinks may contribute more to obesity than food

While the energy density of soft drinks, which are frequently highly calorific, needs to be considered differently from that of solid foods, recent research has demonstrated that consumption of soft drinks is likely to increase normal caloric intake.  When people consume soft drinks, they do not recognise that they have taken in extra energy and compensate by reducing energy from elsewhere in their daily diet, or by expending additional energy; they simply add it on. 

A standard 330 ml can of Coca-Cola contains 139 calories. Thus if a person were to consume a can of Coca-Cola with two meals per day, over a week that would result in an energy surplus of nearly 2,000 calories-more than a whole day’s recommended calorie intake for the average woman, and about  three-quarters of the recommended daily calorie intake for a man. Evidence from the British Soft Drinks Association suggests that children drink an average of 4.7 litres of soft drink per week, of which only 10% are fruit juice or water. 

Consumption of alcohol, particularly amongst women and young people in the UK, has increased dramatically during the past years. Since 1970, alcohol consumption in the UK has increased by 40 per cent. With most alcoholic drinks being at least as calorific as a high-sugar soft drink, such as Coca-Cola, it would seem intuitive that the massive increase in their consumption has had some impact on the nation’s weight. Much attention has focused in recent months on the growing culture of ‘binge drinking’, particularly amongst young people. While the health risks associated with this are well documented, what is less publicised is that drinking five pints of lager over an evening adds an extra 1,135 calories, nearly half a man’s daily energy requirement, and five bottles of an ‘alcopop’ such as Bacardi Breezer contain 990 calories, nearly half a woman’s daily energy requirement. 

Researchers from the Johns Hopkins Bloomberg School of Public Health examined the relationship between beverage consumption among adults and weight change and found that weight loss was positively associated with a reduction in liquid calorie consumption and liquid calorie intake had a stronger impact on weight than solid calorie intake. The results are published in the April 1, 2009, issue of the American Journal of Clinical Nutrition. 

“Both liquid and solid calories were associated with weight change, however, only a reduction in liquid calorie intake was shown to significantly affect weight loss during the 6-month follow up,” said Benjamin Caballero MD, PhD, senior author of the study and a professor with the Bloomberg School’s Department of International Health. “A reduction in liquid calorie intake was associated with a weight loss of 0.25 kg at 6 months and 0.24 kg at 18 months. Among sugar-sweetened beverages, a reduction of 1 serving was associated with a weight loss of 0.5 kg at 6 months and 0.7 kg at 18 months. Of the seven types of beverages examined, sugar-sweetened beverages were the only beverages significantly associated with weight change.”

Researchers conducted a prospective study of 810 adults aged 25-79 years old participating in the PREMIER trial, an 18-month randomized, controlled, behavioural intervention. Caballero along with colleagues from the Johns Hopkins School of Medicine; the National Heart, Lung, and Blood institute; Duke University; the Pennington Biomedical Research Center; the Kaiser Permanente Center for Health Research; the University of Alabama; and Pennsylvania State University measured participant’s weight and height using a calibrated scale and a wall-mounted stadiometer at both 6 and 18 months. Dietary intake was measured by conducting unannounced 24-hour dietary recall interviews by telephone. 

Researchers divided beverages into several categories based on calorie content and nutritional composition: 

• sugar-sweetened beverages (regular soft drinks, fruit drinks, fruit punch, or high-calorie beverages sweetened with sugar)
• diet drinks (diet soda and other “diet” drinks sweetened with artificial sweeteners)
• milk (whole milk, 2 percent reduced-fat milk, 1 percent low-fat milk, and skim milk)
• 100 percent juice (100 percent fruit and vegetable juice)
• coffee and tea with sugar, coffee and tea without sugar and
• alcoholic beverages.

They found that at 37 percent sugar-sweetened beverages were the leading source of liquid calories. 

Consumption of liquid calories from beverages has increased in parallel with the obesity epidemic.

Earlier studies by Bloomberg School researchers project that 75 percent of U.S. adults could be overweight or obese by 2015 and have linked the consumption of sugar-sweetened beverages to the obesity epidemic, which affects two-thirds of adults and increases the risk for adverse health conditions such as type 2 diabetes. 

Researchers recommend limited liquid calorie intake among adults and to reduce sugar-sweetened beverage consumption as a means to accomplish weight loss or avoid excess weight gain. 

“Among beverages, sugar-sweetened beverages was the only beverage type significantly associated with weight change at both the 6- and 18-month follow up periods,” said Liwei Chen, MD, PhD, MHS, lead author of the study and a Bloomberg School graduate. “Changes in the consumption of diet drinks and alcoholic beverages were inversely associated with weight loss, but were not statistically significant. Our study supports policy recommendations and public health efforts to reduce intakes of liquid calories, particularly from sugar-sweetened beverages, in the general population.” 

In the UK, little government attention seems to be given to the impact of soft drink and alcohol consumption on obesity.  The adverse health effects of excess alcohol consumption are well-documented but its effects on weight gain are underestimated. The effect of alcohol on obesity is not even mentioned in the Chief Medical Officer’s recent Annual Public Health Report, which created controversy by suggesting a range of measures to address the nation’s drink problem. 

“Easy access to cheap alcohol is “killing us as never before” and must be curbed with tough licensing laws, price rises and a shift in public opinion that makes being drunk as unacceptable as smoking”.  

Responding to comments from Downing Street that the majority of sensible drinkers should not have to pay for the excessive drinking of the minority, Sir Liam said: “I take a different view as to whether heavy drinking is a minor and insignificant problem.” 

If the UK government is not yet prepared to tackle the well-understood health problems associated with alcohol consumption, we clearly have a long way to go before its effect on obesity reaches the radar screen. 

For information on the effects of different types of drinks on health and creative ideas for healthy drinks, please come to a Cooking for Health course, held throughout the year in Somerset, UK, led by nutrition expert Dr Jane Philpott.