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Chips and fries were the foods most linked to weight gain

Changes in diet and lifestyle and long-term weight gain in women and men.

Overview

Mozaffarian D et al.. N Engl J Med 2011 · PMID 21696306 · DOI 10.1056/NEJMoa1014296

In 120,877 US adults, each extra daily serving of potato chips was linked to 0.8 kg and French fries to 1.5 kg more weight gain over 4 years.

Does the study support the specific claim? No · Methodological quality: moderate

Study explained simply

What did the researchers want to find out?: Find foods linked to weight gain.
How was the study done?: Three cohorts, change analysis.
How many people, animals or samples were studied?: 120,877 adults.
What was actually found?: Chips, potatoes, sugary drinks, meats linked to gain.
How large was the observed effect?: Chips +1.69 lb/4 y per daily serving.
What do the results mean in everyday life?: Chips and fries are not neutral foods.
What are the study's limitations?: Self-report.
What does it say about Elawady's specific claim?: Contradicts unrestricted chips and fries; supports a small refined-grain effect.
Do the results apply to Germany and Europe?: Moderate.
What can explicitly not be concluded from this study?: Cannot prove causation.

Authors: Mozaffarian D et al.
Journal: N Engl J Med
Year: 2011
Identifier: PMID 21696306 DOI 10.1056/NEJMoa1014296 · PMC3151731
Verification: verified – PubMed efetch 2026-10-26; Crossref works API 2026-10-26
Retracted: no
Corrections: none
Extent checked: full text
Conflicts of interest and funding: NIH grants and Searle Scholars Program; first author reported consulting/lecture fees from food companies (full text).

Which dietary and lifestyle changes are associated with long-term weight gain?

Study design: Cohort study – Three prospective cohorts, change-on-change analysis with inverse-variance pooling
Population: US women and men free of chronic disease and not obese at baseline
Country: USA
Period: 1986-2006
Sample size: 120,877
Inclusion and exclusion criteria: Free of chronic disease, not obese

Exposure / intervention: Changes in intake of specific foods per 4-year period
Comparator: No change
Endpoints: Weight change per 4 years
Statistical methods: Multivariable linear regression, pooled

Results: Average gain 3.35 lb per 4 years. Per increased daily serving: potato chips +1.69 lb, potatoes +1.28 lb (French fries +3.35 lb; boiled/baked/mashed +0.57 lb), refined grains +0.39 lb, whole grains -0.37 lb, fruits -0.49 lb, nuts -0.57 lb, yogurt -0.82 lb (full text table).
Absolute risks: not reported
Authors' conclusion: Specific dietary and lifestyle factors are independently associated with long-term weight gain.

Chips +0.77 kg, French fries +1.52 kg, refined grains +0.18 kg per 4 years per extra daily serving (stats/C-GRN-07).

Potato chips and French fries were among the foods most strongly associated with weight gain; refined grains modestly.

Associations; small per-serving effects.

Moderate.

Influential cohort evidence.

Multidimensional assessment
Multidimensional assessment
Authenticity of the source	verified
Methodological quality	moderate
Risk of bias	some concerns
Precision of results	high
Directness	direct
Reproducibility	partly replicated
Consistency with the overall evidence	consistent
Regional transferability	moderate
Adequacy of the interpretation (by the archive)	not applicable

Causality.