Research

Hormonal

Changing dietary fatty acid composition from saturated to unsaturated (monounsaturated/polyunsaturated) does not significantly improve insulin sensitivity in healthy humans or those with NIDDM in short-term controlled trials.

Switching your fat sources (e.g., from butter to olive oil) is healthy for other reasons, but do not expect it to fix insulin resistance or lower blood sugar quickly. Current evidence suggests this change has little to no immediate effect on how your body handles insulin in healthy people or those with Type 2 Diabetes.

GoodRefutesHIGH confidence
controlled dietary intervention studies in humans investigating the effects of different types of fatty acids on insulin sensitivity have so far been negative.
Bengt Vessby · British Journal Of Nutrition · 2000

Why this rating

Based on multiple controlled trials and meta-analyses of short-term interventions, though the author notes potential issues with duration and power.

Source

Dietary fat and insulin action in humans

Bengt Vessby · British Journal Of Nutrition · 2000

DOI 10.1017/s000711450000101x

narrative_reviewCited 290×
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DOI resolved against Crossref · corpus check 2026-06-10

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