How Much Weight Will You Gain?

Summarized by Robert W. Griffith, MD
March 27, 2006

Introduction

The search is on for the causes of the obesity epidemic, in the hopes that something can be done about it on a national scale in the USA. One of the commonly-accused factors is the consumption of sugar-sweetened drinks. Researchers in Spain have now reported just how much weight gain can be expected from consuming such enticements - independent of total energy intake, exercise, and inactivity. This is obviously important for Europeans, whose food habits are rapidly adapting to the US fast-food style of some years back; but the findings have implications for the whole developed world. The study is reported in the American Journal of Clinical Nutrition , and summarized here.

What was done

Scientists at the University of Navarra studied the intake of fast food and sugar-sweetened soft drinks (SSSD) in healthy men and women graduates using a 136-item food-frequency questionnaire. Recruitment stared in 1999, with follow-up every 2 years; this report covers 7,000 participants who had been followed for at least 2 years.

Participants who reported extremely low or high calorie intakes (below 800 or above 3,500 calories a day) were excluded. The surveys included additional questions about medical history, health habits, lifestyle, etc. Data on body weight were self-reported; they included information on the individual's weight for the 5 years prior to the start of the study.

For the purpose of analyses, the participants were divided into two major groups - those who had gained less, and those who had gained more than 3 kg (6½ pounds) in the previous 5 years. In both of these groups, the subjects were classified into one of 5 equal groups, or quintiles, based on their consumption of SSSD; this ranged from below 4 ml/day (0.14 ounces/day) to more than 87.5 ml/day (3 ounces/day).

What was found

The average age of the participants was 41 years; 45% of them were male. Almost half (49.5%) of them increased their weight during the 2-year or more follow-up period. The average change was an increase of 0.64 kg (1½ pounds).

The likelihood of gaining weight was calculated for the highest vs. the lowest quintile of SSSD intakes. In the group who gained more than 3 kg in the 5 years before the study, those who consumed the most SSSD were 1.6 times as likely to gain weight than those who consumed the least SSSD. There was no such difference in the group who had not gained 3 kg in the 5 years before the study.

Eating hamburgers, pizza, and sausages (as indicators of fast food consumption) led to a 1.2 times increased likelihood of weight gain.

What these findings mean

The results of this study aren't too surprising. Links between increased consumption of sugared soft drinks and fast foods and weight gain are not unexpected. However, they serve as a warning to European and other developed countries: following the US example of dietary lifestyle and you can expect to achieve the US overweight and obesity numbers.

The actual rate of increase in weight in those in the high-consumption quintiles is similar to that reported for results from another recently-published US study ¹ - frequent fast-food eating with associated SSSD intake causes a weight increase of approximately 0.3 kg (over ½ pound) each year.

Neither of the two recent studies report whether weight gain was additionally linked to a sedentary lifestyle. However, using the 'calories-in' minus 'calories-out' equation, physical activity can certainly compensate for the fast-food habit to a certain extent. Without exercise, you can probably expect to pack on ½ pound a year, unless you shun sodas and fast food.

Source

• Predictors of weight gain in a Mediterranean cohort: the Seguimiento Universidad de Navarra Study. M. Bes-Rastrallo, A. Sanchez-Villegas, E. Gomez-Gracia,  et al., Am J Clin Nutr, 2006, vol. 83, pp. 362--370

Footnotes
1. Fast-food habits, weight gain, and insulin resistance (the CARDIA study): 15-year prospective analysis. MA. Pereira, AI. Kartashov, CB. Ebberling,  et al, Lancet, 2005, vol. 365, pp. 36--42

Related Links
The Fast-Food Habit
Eat as Much as You Like and Lose Weight?
How Likely Are You To Become Obese?

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