"Obviously, no magic formula exists for weight loss, but our results indicated that a diet containing more than average amounts of fiber, complex carbohydrate, and fruit was associated with normal body fat stores and standard weight for height," wrote lead author Jaimie Davis in the Journal of the American Dietetic Association.
Over 300m adults are obese worldwide, according to latest statistics from the WHO and the International Obesity Task Force. About one-quarter of the US adult population is said to be obese, with rates in Western Europe on the rise although not yet at similar levels.
The new study, by researchers from the University of Texas, used food frequency questionnaires to compare the diets of 52 overweight/obese volunteers (average BMI of 33.7 kg per square metre, average age 39.7, 18 men, 34 women) and 52 normal weight controls, matched for age, sex, and height.
Comparison of the diets on a macronutrient level showed that the obese subjects generally had diets that were higher in fat (five per cent), higher in protein (0.9 per cent) and lower in carbohydrates (7.1 per cent).
"A key finding of our study was that diet composition between overweight/obese adults and their normal-weight counterparts differed substantially and may have played a vital role in promoting or preventing obesity," said Davis.
Dietary fiber was highlighted by the researchers as "the only nutrient that when expressed by absolute weight accounted for a significant amount of the variance in body fat."
The normal group consumed about three grams more of fiber per day than their obese counterparts, but still fell well short of the 32 grams of fiber per day recommended by the US National Fiber Council. The normal group's intake was in-line with a survey by Columbia University, that showed the average intake in the US was about 12.5 grams a day.
"Although dietary fiber accounted for a rather small amount of variance in body fat, three to five per cent, the association provides useful information that could aid in developing weight-loss interventions," concluded the researchers.
The researchers also found that the obese group ate less fruit servings per day, while dairy and vegetable intake was similar between the groups.
This result is also in line with an earlier study published in the American Journal of Clinical Nutrition (Vol. 83, pp. 760-766) that reported that high dietary fiber intake, both insoluble and soluble could reduce levels of C-reactive protein (CRP), a known marker for inflammation that is produced in the liver. Increased levels of CRP are a good predictor for the onset of both type-2 diabetes and cardiovascular disease.