Changes in Types of Dietary Fats Influence Long-term Weight Change in US Women and Men

Abstract

Background: The relation between dietary fat intake and body weight remains controversial. Few studies have examined long-term changes in types of dietary fat and weight change in longitudinal studies.

Objective: The objective of this study was to examine associations between intake of different types of fat and long-term weight change in US women and men.

Methods: The association between changes in consumption of varying types of fat and weight change was examined every 4 y through the use of multivariate models adjusted for age, baseline body mass index, and change in percentage energy from protein, intake of cereal fiber, fruits, and vegetables, alcohol use, and other lifestyle covariates in 3 prospective US cohorts, including 121,335 men and women free of diabetes, cardiovascular disease, cancer, or obesity over a 20- to 24-y follow-up. Dietary intakes and body weight were assessed via validated questionnaires. Cohort-specific results were pooled with the use of a random-effect meta-analysis.

Results: Compared with equivalent changes in carbohydrate intake, a 5% increase in energy from saturated fatty acid (SFA) and a 1% increase in energy from trans-fat were associated with 0.61 kg (95% CI: 0.54, 0.68 kg) and 0.69 kg (95% CI: 0.56, 0.84 kg) greater weight gain per 4-y period, respectively. A 5% increase in energy from polyunsaturated fatty acid (PUFA) was associated with less weight gain (-0.55 kg; 95% CI: -0.81, -0.29 kg). Increased intake of monounsaturated fatty acid (MUFA) from animal sources by 1% was associated with weight gain of 0.29 kg (95% CI: 0.25, 0.33 kg), whereas MUFA from plant sources was not associated with weight gain.

Conclusions: Different dietary fats have divergent associations with long-term weight change in US men and women. Replacing saturated and trans-fats with unsaturated fats, especially PUFAs, contributes to the prevention of age-related weight gain. These trials were registered at clinicaltrials.gov as NCT00005152 and NCT00005182.

FIGURE 1

Weight change (kilograms) per 4-y period associated with the increase in percentage of energy from total fat, animal-source fat, vegetable-source fat, SFAs, trans-fat, MUFAs, and PUFAs from a meta-analysis of 3 prospective cohorts of US women and men. HPFS, n = 25,052; NHS, n = 49,932; NHS II, n = 46,371; pooled, n = 121,355. Values are mean changes (95% CIs). Number of observations = 398,809. Multivariable model adjusted for age, baseline BMI at the beginning of each 4-y period, baseline hours of sitting, sleep duration, changes in intake of protein (percentage of total energy), cereal fiber, fruit, and vegetables, smoking status (no, current, or past), physical activity, and alcohol use (Model 2). Animal fat and vegetable fat were mutually adjusted in Model 2. SFA, trans-fat, MUFA, and PUFA were mutually adjusted in Model 2. E, energy; HPFS, Health Professionals Follow-up Study; NHS, Nurses’ Health Study.

FIGURE 2

Weight change (kilograms) per 4-y period associated with the increase in percentage of energy from animal-source MUFA, plant-source MUFA, n–3 PUFAs, and n–6 PUFAs from a meta-analysis of 3 prospective cohorts of US women and men. HPFS, n = 25,052; NHS, n = 49,932; NHS II, n = 46,371; pooled, n = 121,355. Values are mean changes (95% CIs). Number of observations = 398,809. Multivariable model adjusted for age, baseline BMI at the beginning of each 4-y period, baseline hours of sitting, sleep duration, changes in intake of protein (percentage of total energy), cereal fiber, fruit, and vegetables, smoking status (no, current, or past), physical activity, and alcohol use (Model 2). Plant-source MUFA and animal-source MUFA were mutually adjusted for trans-fat and PUFA in Model 2. n–6 PUFA was adjusted for SFA, trans-fat, and MUFA in Model 2. Linoleic acid was adjusted for SFA, trans-fat, and MUFA in Model 2. n–3 PUFA was adjusted for SFA, trans-fat, and MUFA in Model 2. Marine origin n–3 and plant n–3 PUFA (ALA) were mutually adjusted for SFA, trans-fat, and MUFA in Model 2. ALA, α-linolenic acid; HPFS, Health Professionals Follow-up Study; NHS, Nurses’ Health Study.