Taking extra protein shakes after losing weight doesn’t help you keep the weight off any better than eating the normal amount of protein in your daily diet.
Scientific Claim
Protein supplementation (45–48 g/day from whey, whey with calcium, or soy) does not improve weight maintenance after weight loss in obese adults compared to normal dietary protein intake (0.8–1.0 g·kg⁻¹·d⁻¹), as evidenced by similar mean weight regain across all groups (range: 1.76–2.23 kg) after 24 weeks.
Original Statement
“The control and 3 protein supplements did not result in different mean ± SD weight regains (whey+: 2.19 ± 4.6 kg; whey: 2.01 ± 4.6 kg; soy: 1.76 ± 4.7 kg; and control: 2.23 ± 3.8 kg; P = 0.96)”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design supports claim
Appropriate Language Strength
probability
Can suggest probability/likelihood
Assessment Explanation
The study is an RCT, which supports causal inference, but the abstract lacks full methodological transparency (e.g., attrition bias, equivalence testing). Therefore, 'does not improve' is appropriately softened to probabilistic language.
More Accurate Statement
“Protein supplementation (45–48 g/day from whey, whey with calcium, or soy) probably does not improve weight maintenance after weight loss in obese adults compared to normal dietary protein intake (0.8–1.0 g·kg⁻¹·d⁻¹), as evidenced by similar mean weight regain across all groups (range: 1.76–2.23 kg) after 24 weeks.”
Gold Standard Evidence Needed
According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.
Systematic Review & Meta-AnalysisLevel 1aWhether protein supplementation consistently fails to improve weight maintenance across diverse populations, dosages, and durations after weight loss.
Whether protein supplementation consistently fails to improve weight maintenance across diverse populations, dosages, and durations after weight loss.
What This Would Prove
Whether protein supplementation consistently fails to improve weight maintenance across diverse populations, dosages, and durations after weight loss.
Ideal Study Design
A systematic review and meta-analysis of 15+ high-quality RCTs (n≥100 per trial) comparing protein supplements (≥40 g/day) vs. control during 20–24 week weight maintenance phases in adults (BMI 27–40) with primary outcome of weight regain, using intention-to-treat analysis and standardized body composition measures (DXA).
Limitation: Cannot establish biological mechanisms or identify subgroups that may benefit.
Randomized Controlled TrialLevel 1bIn EvidenceCausal effect of protein supplementation on weight maintenance in obese adults under controlled conditions.
Causal effect of protein supplementation on weight maintenance in obese adults under controlled conditions.
What This Would Prove
Causal effect of protein supplementation on weight maintenance in obese adults under controlled conditions.
Ideal Study Design
A double-blind, placebo-controlled RCT of 300+ obese adults (BMI 27–40) randomized to 48 g/day whey protein vs. maltodextrin placebo during a 24-week weight maintenance phase after 8-week weight loss, with primary outcome: weight regain measured by DXA, secondary: appetite and energy expenditure, with 95% compliance and full follow-up.
Limitation: Limited generalizability to real-world settings and long-term (>1 year) outcomes.
Prospective Cohort StudyLevel 2bLong-term association between habitual protein supplement use and weight regain in real-world populations after weight loss.
Long-term association between habitual protein supplement use and weight regain in real-world populations after weight loss.
What This Would Prove
Long-term association between habitual protein supplement use and weight regain in real-world populations after weight loss.
Ideal Study Design
A 3-year prospective cohort of 1000+ adults who lost ≥5% body weight, tracking self-reported protein supplement use, dietary intake, and weight changes quarterly, adjusting for physical activity, sleep, and socioeconomic confounders.
Limitation: Cannot prove causation due to potential confounding and self-report bias.
Evidence from Studies
Supporting (1)
Scientists tested if drinking protein shakes after losing weight helps keep the weight off, and found that people who took protein shakes regained about the same amount of weight as those who ate normal amounts of protein—so the shakes didn’t help.