Table 1.

Description and coding of the covariates used in the meta-regression analysis.

Covariate	Description	Coding
Mean age	Mean age of the participants	Years (continuous variable; range 20.0-69.1)
Proportion of men	Relative proportion of men from 0% to 100%	Range 0-1; the scale has been changed
Analysis of prevention	Secondary and tertiary prevention were compared with primary prevention	S: secondary prevention; T: tertiary prevention
Length of the intervention	Length of the intervention	Weeks (continuous variable; range 4-8)
Personal goals	If the intervention included setting personal goals for the weight loss intervention	No (0) or Yes (1; dichotomous variable)
Self-reporting	If the intervention included self-reporting of values needed in the study (eg, weight, steps, and diet)	No (0) or Yes (1; dichotomous variable)
Personal feedback	If the participants received personal feedback about their progress (eg, weight loss or physical activity)	No (0) or Yes (1; dichotomous variable)
Using theory	If the intervention used motivational or behavior change theories	No (0) or Yes (1; dichotomous variable)
Content of the control group	0=wait-list or no-intervention group 1=usual care or content of the control group has not been mentioned 2=usual care plus minimal guidance (eg, pamphlets) 3=paper instructions 4=paper instructions plus minimal instructions (eg, introduction lessons) 5=other intervention concerning weight loss (eg, annual physician appointment and fitness test)	Six-level factor using the wait-list group or no-intervention group as a reference group (categorical variable)
Quality of the studies	The level of quality assessment	Range 0-13 (continuous variable) [38]