Early Weight Loss and Other Factors Associated With Clinically Significant Weight Loss in Two Commercial Weight Loss Programmes.

This secondary analysis assessed potential factors associated with achieving ≥ 5% or ≥ 10% weight loss among adults in a clinical trial evaluating two commercial weight loss programmes. Participants [n = 124, 45.7 (13.1) years, 20.2% male, BMI 34.4 (3.4) kg/m2] were randomised to the Medifast or OPTAVIA weight loss programme, both of which included meal replacements and behavioural support. Multivariable logistic regression analyses were used to assess early weight loss thresholds (percent weight loss at 2 and 4 weeks) and potential demographic, anthropometric, behavioural, and lifestyle factors associated with ≥ 5% or ≥ 10% weight loss at 16 weeks. Age, education, ≥ 1% weight loss by Week 2, ≥ 2% weight loss by Week 4, number of support contacts and programme adherence through Week 4 were significantly (p < 0.05) associated with achieving ≥ 5% weight loss. Participants losing ≥ 2% by Week 4 had 24.6 (95% CI: 2.49, 243) times greater odds of losing ≥ 5% by Week 16. For ≥ 10% weight loss at 16 weeks, positive factors associated included age, assignment to the OPTAVIA programme, ≥ 3% weight loss by Week 4 and programme adherence through Week 4 (p < 0.05). Participants losing ≥ 3% by Week 4 had 19.4 (95% CI: 2.02, 186) times greater odds of losing ≥ 10%. While several variables were significantly associated with achieving clinically significant weight loss, 4-week weight loss was strongest. These results may be useful for early identification of individuals at risk for failing to achieve clinically significant weight loss who may benefit from intensification of counselling to assist in attaining weight loss goals.