Swedish obese subjects (SOS): an obesity intervention study with a nutritional perspective

Swedish Obese Subjects (SOS) is a multidisciplinary project involving aspects of obesity ranging from description of the severely obese state to effects of surgical intervention on long-term mortality and morbidity. Dietary studies, which represent an integral part of SOS research activities, are the focus of this review.

Due to the large number of obese subjects included in the SOS data bases ( > 5000), an early priority of the project was to develop a dietary assessment method which: (i) described usual intake patterns; (ii) could be self-administered by subjects and rapidly processed; and (iii) was equally valid in obese and non-obese individuals.

The SOS method has met these requirements and is now being completed by all subjects at baseline and during the intervention, and by a non-obese reference population. A number of dietary features distinguishing obese subjects have emerged, including: elevated intakes of energy and energy-percent fat; low consumption of alcohol, fruits and vegetables; high dietary disinhibition; frequent consumption of light meals and snacks; and night eating. In the surgical intervention group, a relatively high consumption of sweet foods was associated with better weight loss and maintenance.

The SOS method appears to be less susceptible to obesity-related under-reporting than traditional dietary methods, and if the distribution of foods and nutrients can be assumed to be as unbiased as the energy intakes, this method should make it possible to capture associations between diet and obesity-related diseases in the future.