Fat has been shown to be a powerful modifier of dietary glycemic response (Flint et al 2004). But other research shows addition of fat to high GI meals worsens insulinemic response (Gannon et al 1993). The author hypothesized that researched insulin response was more related to excessive meal size (50+ gms of both carbohydrate and fat) than to fat content per se.

The current study compared starch or sugar based nonfat 50 gm carb meals (∼250 kcal) with meals containing 30 gm amounts of both fat and carb (∼450 kcal) in 12 healthy 21-75 year old volunteers (6-8 per subgroup) without glucose intolerance. Size of subgroups was similar to that used in establishing the glycemic index (Jenkins et al 1981). Each subject served as their own control. Despite the larger meal size, the balanced carb/fat meals had lower glycemic and insulin responses, with p values of 0.009 and 0.016 for glycemic response, and 0.014 and 0.0275 for insulin response to starch and sugar-based meals, respectively (Wilcoxson, one tailed). Post-study interviews also demonstrated that subjects preferred the balanced meals.

This pilot study has demonstrated that adding fat to moderate sized meals lowered, not raised, insulin levels, even when compared to much smaller nonfat meals. It also confirms previous research that fat lowers glycemic response and improves palatability.

Taken together, these findings support further research into the potential benefit of balanced carb/fat meal combinations. Such meals might improve diet sustainability as well as efficacy. Future research can explore other fat types/amounts, and evaluate the utility of this concept in real world dietary management.


D.K. Jass: None.

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