Now you might be thinking, “Oh great, another obesity study that confirms what we already know; obese people eat too much and exercise too little.” However this study was different. Unlike the typical obesity study, which consist of subjecting overweight individuals to a battery of tests and questionnaires in an attempt to identify common obesity traits, this particular study sought to identify what behaviours precipitate the development of obesity.
In order to do so, the researchers tracked hundreds of participants between the ages of 18-64, having a wide range of BMIs for a six-year time period. As you can imagine, this approach to research is time consuming and expensive, which is why you rarely see studies like this. However, unlike the typical approach, study some people for 3 months then make a grandiose claim about the mechanics of weight control, at the end of the day, these researchers can actually make educated statements about how long-term weight control might work in the real world.
So what did they find? Unsurprisingly, during the initial stratification, overweight individuals (BMI over 25 kg/m2) were found to exhibit 9 traits in common:
- short sleep duration
- high disinhibition eating behaviour
- low dietary calcium intake
- high susceptibility to hunger behaviour
- nonparticipation in high-intensity physical exercise
- high dietary restraint behaviour
- nonconsumption of multivitamin and dietary supplements
- high dietary lipid intake
- high alcohol intake
These results are quite similar to other obesity studies as even a quick scan at this list reveals all our usual “fattening” culprits. However, the problem with this list is that it consists of only correlational data. In other words, it doesn’t tell us if any of those behaviours cause obesity. So the question remains, are fat people fat because they eat too much and don’t exercise enough… or do people eat too much and avoid exercise because they are fat? It’s a subtle distinction, but an important one if we hope to design actual effective interventions.
After tracking the individuals of various BMIs for six years, these researchers discovered that only 3 of those 9 traits actually predicted which formerly non-obese individuals became overweight over the course of the study. Can you guess which ones?
If you guessed nonparticipation in high-intensity physical activity, high dietary fat intake and high alcohol intake, you are 100% incorrect.
What?!?! A lack of exercise and overconsuming fatty foods and alcohol aren’t prime predictors of long-term weight gain? No, at least not according to these data.
It turns out that three traits that predicted weight gain were (ranked in order of importance):
- short sleep duration (< 6 hours/day)
- high disinhibition eating behaviour
- low dietary calcium intake (< 600 mg/day)
And the first two were by far and away the strongest predictors.
If we stop and think about this for a second, a couple of conclusions come to mind. Firstly, none of our predictors for future weight gain have a direct caloric value. This is both surprising and troubling, since it runs counter to everything we like to preach about weight control.
Secondly, our strongest predictor, a lack of sleep, has nothing to do with our energy balance equation at all, at least not directly! Although sleep isn’t a huge calorie expending activity, we know that a lack of sleep has catastrophic effects on hormonal control (insulin, leptin, growth hormone, cortisol… etc).
In fact, sleep is so critical to the maintenance of proper hormonal regulation that even a few nights of compromised sleep can result in blood sugar dysregulation comparable to what we’d see in a pre-diabetic! Clearly, missing out on sleep can cripple even the best designed diet and exercise program.
But excess fat gain is not strictly about hormonal dysregulation. Predictive traits number two and three are more reflective of a negative relationship with high-quality food. Obviously “high disinhibition eating behaviour” is indicative of a binge-eating pattern, which we can all agree is a recipe for failure.
Often, we mistakenly label all high-calorie foods as “bingeable”, however I have yet to encounter any individual who gets an insatiable craving for olive oil or steel-cut oats. Clearly, binge eating is only possible in the presence of synthetic high-sugar, high fat foods that are both high in calories and low in nutrition.
Although this was just one study, I found it interesting that none of the commonly assumed major risk factors ie. eating fatty foods, drinking too much or a lack of exercise, showed much predictive power for future weight gain. Only time will tell whether this was simply an isolated finding, however, for the moment it makes us question if we’ve been demonizing the wrong causes.
References
1. Chaput et al. (2009). Risk Factors for Adult Overweight and Obesity in the Quebec Family Study: Have We Been Barking Up the Wrong Tree? Obesity, 17, 1964-1970.
Graeme Thomas MSc. is a nutritionist and University instructor based out of London, Ontario. To learn more about how to truly control body weight, visit his blog at http://graemethomasonline.com/blog.
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