The Study
The Effect of Starting the Protein-Sparing Modified Fast on Weight Change over 5 years
This study watched what happened when people chose to eat a special diet called PSMF versus other diets, but it didn’t force anyone to pick one. So we can’t say the diet itself made people lose weight — maybe the people who picked it were just more determined or had more support. It shows a pattern, but not proof.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
Some people try a super-strict diet called PSMF to lose weight fast. This study looked at what happened to them over 5 years compared to people who tried other diets.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 559 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1The fast start of PSMF is impressive, but most people regain the weight.
- 2The real secret to long-term success isn't the diet you pick—it's whether you lose at least 3% in the first few months.
- 3At 1 year: PSMF users lost more weight (55% lost 5%+ vs.
- 420% on other diets).
- 5At 5 years: Both groups had similar results (34% vs.
- 629% lost 5%+).
- 7Only 1 in 10 kept off 15%+ of their weight.
- 8If you lost 3% in the first 3 months, you were much more likely to lose weight long-term—no matter which diet you picked.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of General Internal Medicine
Year
2020
Authors
E. Pfoh, G. Lowenthal, L. Jeffers, B. Burguera, D. Cetin, Bo Hu, N. Gupta, Marven Cantave, M. Rothberg
Related Content
Claims (5)
Obese adults who start the protein-sparing modified fast lose 6% more weight than those on other diets after one year, but by four years, both groups have lost the same amount of weight.
Obese adults who lose at least 3% of their body weight in the first three months of dieting tend to lose more weight over five years than those who do not, no matter what diet they follow.
Among obese adults, 55% lose at least 5% of their body weight after one year on a protein-sparing modified fast, compared to 20% on other diets. After five years, both groups have similar rates of weight loss: 34% and 29% respectively.
People who follow a very low-calorie protein-sparing modified fast diet lose weight faster at first than those on other diets, but after four to five years, the amount of weight kept off is about the same regardless of the diet used.
Among obese adults who start a protein-sparing modified fast, fewer than 10% keep off at least 15% of their body weight five years later.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.