Background: The strength of the association between achieving clinically significant weight loss and remission of metabolic complications remains unclear. This study aimed to investigate the effect of weight loss on remission of metabolic risk factors.
Methods: A systematic review searched Embase, Medline, Web of Science, and Google Scholar databases (up to April 2023) for studies comparing the effects of ≥5% versus <5% total weight loss (%TWL) for at least 12 months. Mean differences (MD) and risk ratios (RR) with 95% confidence intervals (95% CI) were calculated for the meta-analysis.
Results: A total of 39 comparative studies (23 randomised controlled trials, 12 observational studies, and four non-randomized experimental studies) published between 2003 and July 2023 were reviewed. Compared to <5%TWL, ≥5%TWL had a higher RR of type 2 diabetes remission (8.18:5.09,13.15; I²=76.49%), hypertension remission (2.53:1.06,6.06; I²=77.26%), and metabolic syndrome remission (5.61:1.62 to 19.49; I2 = 70.19%). Predictors of type 2 diabetes remission included %TWL (1.13:1.09,1.17) and ≥15%TWL (5.11:3.18,8.22). Compared to <5%TWL, ≥5%TWL participants achieved significant MDs in HbA1c (-1.16:-1.54,-0.78), FPG (-1.24:-2.00,-0.49), SBP (-3.79:-6.04,-1.54), triglycerides (-0.30:-0.49,-0.10), HDL-cholesterol (0.09:0.04,0.14) and fasting insulin (-1.99:-3.79,-0.19); Predictors for MDs in HbA1c included %TWL (-0.08%:-0.11,-0.06), ≥15%TWL (-0.86:-1.11,-0.60), surgery (-1.22:-1.76,-0.68), and length of follow-up ≥36 (-1.02:-1.85,-0.19). Predictors for MDs in FPG included %TWL (-0.12: -0.07,-0.18), ≥15%TWL (-1.62:-2.21,-1.03), and quality score ≥75% (1.31:0.04,2.59). Predictors for MDs in SBP included %TWL (-0.46:-0.73, -0.20), ≥15%TWL (-10.54:-19.28,-1.79), and surgery (-7.13:-12.36,-1.91).Predictors for MD in triglycerides included %TWL (-0.05:-0.07,-0.04), ≥15%TWL (-0.59:-0.73,-0.44), and surgery (-0.47:-0.70,-0.29). Predictors for MD in HDL-Cholesterol included %TWL(0.01:0.01,0.02), ≥15%TWL(0.19:0.15,0.23), and surgery (0.14:0.07,0.20).
Conclusions: Remission of metabolic complications and improvements in HbA1c, blood pressure, lipids, and fasting insulin were observed following ≥5%TWL in obesity-patients. Factors like the %TWL achieved (particularly ≥15%), surgical interventions, and duration of follow-up predict these outcomes. Clinical practice guidelines should be updated to reflect these findings.