Background: Current guidelines for obesity management emphasize the improvements in health risks associated with weight losses of 5-10% initial weight. However, most of the data is derived from periods of acute weight loss and may not represent the true effect in the longer term or in obese but otherwise healthy individuals. This study examines the temporal changes in risk factors for cardiovascular disease with weight change over 52 weeks.
Methods: In total, 57 overweight women (age 43.7 +/- 9.1 years, mean BMI of 31.7 kg/m2, range 27.2-38.5 kg/m2) with no other significant medical history, entered a milk-based, low-energy weight loss programme for 12 weeks and were then monitored without further intervention until 52 weeks. Weight, fat mass, fasting plasma insulin, lipids and blood pressure were measured at 0, 12, 24 and 52 weeks.
Results: The mean weight change in sequential periods was -11.6% (p < 0.0001), +1.1% (p = 0.02) and +5.2% (p < 0.0001). The change from baseline to 1 year being -6.0% (p < 0.0001) an 11% (p < 0.0001) reduction in initial body fat mass. Initial weight loss (0-12 weeks) was positively correlated with greater longer term weight loss (0-52 weeks, r = 0.75, p < 0.0001) and not with weight regain (12-52 weeks, r = 0.14, p = 0.28). Despite significant improvements in insulin sensitivity, lipid profile and blood pressure (BP) with acute weight loss, in the group overall, only benefits in BP were maintained after 52 weeks. However, improvements in insulin sensitivity were sustained in those who maintained more than 5% weight loss, and those with higher baseline metabolic risk had greater benefits with weight loss. Change in waist circumference was better than BMI or fat mass in predicting improvements in metabolic risk in these obese women.
Conclusions: This study suggests, in otherwise apparently healthy obese women, the rationale of targeting individuals most likely to benefit from weight management. Most importantly it highlights the need to focus on achieving initial weight losses of greater than 10% to maintain longer term losses of at least 5% and the associated health benefits.