Effects of surgically induced weight loss on cardiovascular risk factors. Results from the intervention study Swedish Obese Subjects

Abstract: Aims: To investigate the effects of large maintained weight losses on body composition, adipose tissue distribution and cardiovascular risk factors, i.e. systolic blood pressure, diastolic blood pressure, glucose, insulin, triglycerides, cholesterol, HDL-cholesterol and uric acid.Methods: Swedish Obese Subjects (SOS) is an ongoing prospective intervention study of obesity. The intervention consists of three types of bariatric surgery. The matched control group receives conventional anti-obesity treatment at primary health care centres. Inclusion criteria for the intervention study are age 37 to 60 years, BMI '34 kg/m2 for men and '38 kg/m2 for women. Ultimately, the two treatment groups will contain 2000 individuals each and the follow-up will be at least 10 years. The use of anthropometric equations, calibrated by means of a multicompartment CT technique, made it possible to estimate lean body mass (LBM), subcutaneous (SAT) and visceral adipose tissue (VAT) masses from weight, height and the sagittal diameter with errors less than 22%.Results: Two risk patterns were identified. One body composition risk factor pattern, in which the VAT and SAT masses were positively related to risk factors, while LBM showed negative associations. The other pattern was a subcutaneous adipose tissue distribution risk factor pattern. SAT in the upper part of the body as estimated by neck girth was positively associated to cardiovascular risk factors, while the reverse was true for a lower body SAT distribution as estimated by thigh girth.All risk factors except cholesterol were markedly improved two years after bariatric surgery. The two-year incidence of diabetes was reduced 30-fold after a 23% weight loss. In an eight-year perspective, surgically treated patients had lost 16% of their initial body weight while the controls had gained 1%. Surgical treatment reduced the eight-year incidence of diabetes five-fold while it had no effect on the incidence of hypertension. The more pronounced increase in pulse pressure by age seen in the obese could be modified by weight reducing gastric surgery.Conclusions: Body composition and adipose tissue distribution are closely related to cardiovascular risk factors, also in the severely obese. The metabolic profile is markedly improved by gastric surgery. The effect of surgery on the increasing pulse pressure indicates that the atherosclerotic process may be slowed down by weight reduction.