Sunday, March 08, 2009

Eat Less, Weigh Less (who knew?)

After oh-so-many years in a job that demands the reading of a lot of health research, I can’t help but notice that certain themes pop up with predictable regularity. Practically every week a plant compound is outed (or re-outed) as an essential cancer/heart disease/depression/dementia/obesity/aging preventative. It’s almost enough to make you conclude that humans are supposed to eat lots of plants. And, time and again, research seems to suggest that relying on processed foods for nutrition is a very good way to become fat/sick/dumb and old. How novel. What, oh what, could we possibly conclude from that?? Then, four or five times a year, a research facility trotts out a ‘this diet vs. that diet’ study that invariably concludes that low-carb diets create fast fatloss, but that for long term results, what counts is the calorie. You have to eat less of them than you burn and your body does not significantly care where those calories come from. Nobody said life was fair. Sorry.

This week, right on cue, my newsletter arrived bearing a synopsis of a new study which let four slightly different diets slug it out for two years in the real world. Ever helpful Mr McSmarty Brad Pilon inadvertently did my homework for me and posted a link to the actual Harvard School of Public Health Press Release:

Diets That Reduce Calories Lead to Weight Loss, Regardless of Carbohydrate, Protein or Fat Content.

The title desciptively sums up the findings of the study, however the finer details are worth a second look.

A large trial group (811 individuals) were divided into four groups, each of which was assigned a diet that was either 20% or 40% fat, 15% or 25% protein and 35%, 45%, 55% or 65% carbohydrate. The diet aimed for a calorie reduction of 750 calories per day below maintenance and was designed for heart healthiness – high in fruit, veges, wholegrains and low in saturated fats. In other words, this was not a diet that let the participants swap out their wholegrain bread for chocolate and record it in their journal as a ‘carb’. They each did 90 minutes of unspecified exercise per week. After two years, and a 1.8kg regain from the 6 month point, the average individual weightloss was 4kg, no matter which diet they were on. However (and this is iiiiiinteresting), among those that took full advantage of the counseling that was offered, the average weightloss was about 10kg. The conclusions of this two year study are that calories matter more than macronutrient composition of an otherwise healthy, calorie reduced diet (uh huh) and that social support can make a huge contribution to the longterm success of a fatloss program.

I’m going to crank on at length about my viewpoint on calories in my next post, so I won’t labour the point now, especially when I don’t think it’s the main point. The fact that a reduced calorie diet leads to fatloss is not groundbreaking news, not even when a PhD dedicates two years to proving it. What made me perk up my ears about the Harvard study is the documented proof of what every dieter knows – food is actually quite easy, the real battle is in the mind. Long term fatloss requires long term behaviour change and the human brain prefers to stick with familiar habits, even if they are bad habits. How interesting to read a study that shows such a dramatic benefit when the psychological aspect of fatloss is also taken seriously. I wonder why this important finding is only mentioned in the very last paragraph of the press release? Perhaps it was a curve ball. Scientists probably spend as much, if not more, time as the rest of us scratching their heads about the mysterious magnetism between the human machine and the cadbury creme egg. Perhaps, like most dieters, they were hoping it would be as simple as eat less, weigh less. Wouldn't that be nice?

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