Evidence That Obesity Risk Factor Potencies Are Weight Dependent, a Phenomenon That May Explain Accelerated Weight Gain in Western Societies

Abstract

Background We have shown that individuals at the highest percentiles of the body mass index (BMI) distribution (i.e., most overweight) experience greater increases in body weight from sedentary lifestyle than those from the lowest percentiles. The purpose of the current analyses was to assess whether recent, accelerated increases in obesity could potentially be due to increased vulnerability to obesity risk factors as the population has become more overweight.Methodology/Principal FindingsQuantile regression was used to compare BMI population percentiles to obesity risk factors (lower education, diets characterized by high-meat/low-fruit content, parental adiposity) in two independent samples of men (N1 = 3,513, N2 = 11,365) and women (N1 = 15,809, N2 = 10,159). The samples were subsets of the National Walkers' (Study 1) and Runners' (Study 2) Health Studies whose physical activities fell short of nationally recommended activity levels. The data were adjusted for age, race, and any residual effects of physical activity. The regression slopes for BMI vs. education, diet, and family history became progressively stronger from the lowest (e.g., 5th, 6th…) to the highest (e.g., …, 94th, 95th) BMI percentiles. Compared to the 10th BMI percentile, their effects on the 90th BMI percentile were: 1) 2.7- to 8.6-fold greater in women and 2.0- to 2.4-fold greater in men for education; 2) 3.6- to 4.8-fold greater in women and 1.7- to 2.7-fold greater in men for diet; and 3) 2.0- to 2.6-fold greater in women and 1.7-fold greater in men for family history.Conclusions/SignificanceThus we propose risk factors that produce little weight gain in lean individuals may become more potent with increasing adiposity. This leads us to hypothesize that an individual's obesity is itself a major component of their obesogenic environment, and that, the cycle of weight gain and increased sensitivity to obesity risk factors may partly explain recent increases in obesity in western societies.

Body mass index gain between ages 20 and 40 years and lifestyle characteristics of men at ages 40–60 years: The Adventist Health Study-2

“…This suggests that men who gain more weight are likely to be engaged in lifestyle behaviors that are likely to promote further increase in BMI. These findings are concerning in light of evidence indicating that obesity leads to increased vulnerability to risk factors that cause obesity [25]. Diet and activity were also associated with attained BMI.…”

Perceived current and ideal body size in female undergraduates

“…There are several possibilities as to why females in this sample underestimated their current body size. Due to the growing amount of obesity in Western world, it is possible that women perceive their bodies as smaller because the body size that is considered normal or typical is getting larger (Ogden, Yanovski, Carroll, & Flegal, 2007;Twells, Gregory, Reddigan, & Midodzi, 2014;Wang, Beydoun, Liang, Caballero, & Kumanyika, 2008;Williams, 2011). Twells et al (2014), for example, reported that in 2011 33.6% of Canadian adults reported being overweight ) and 18.3% reported being obese (BMI N30), and that these numbers will continue to rise without intervention.…”

How important are determinants of obesity measured at the individual level for explaining geographic variation in body mass index distributions? Observational evidence from Canada using Quantile Regression and Blinder-Oaxaca Decomposition

“…For example, the association between local fast food prices and BMI at the county level in the USA had the largest magnitude association for the heaviest individuals:17 a $1 decrease in the price of fast food was associated with a 0.1 kg/m 2 increase in average BMI for males, but a 1.0 kg/m 2 increase in BMI for those at the 75th and 90th centiles of BMI. Other American studies have found associations that change across the BMI distribution for food stamp programme participation among females (an increase of 1.6 kg/m 2 on average, but an increase of 2.9 kg/m 2 at the 90th centile of BMI)18 and education (one additional year of education was associated with a 0.165 kg/m 2 decrease in BMI for females at the median BMI level, and a 0.3 kg/m 2 decrease in BMI for females at the 90th centile of BMI) 19. Analysis of Canadian BMI data showed a negative association between BMI and education for males and females on average, and that association was stronger for females at the 60th centile and up 20.…”