The Science Behind Weight Loss (Part 1)

joggingOver the next few weeks I am going to talk about the science behind weight loss. There are a lot of things said about losing weight that appear on the surface to make sense, they have the appearance of science and fit in with our own ideas of how to lose weight. Many people and organisations will try to tell you ‘the secret’ of losing weight but the truth is that there are no secrets.  The facts behind gaining and maintaining a healthy weight are simple and straight forward. In fact some of the weight loss articles out there these days are getting a just little strange and point to exotic and often expensive weight loss supplements.   If instead, you investigate new scientific studies, you will find that they start to reveal how metabolism works and they are valuable for what they reveal.  Unfortunately there is always someone out there who will use this information to promote products that have very little science to show they are effective.  Often organisations or groups will use celebrities or sporting stars in there promotions to imply the efficacy of their product or technique. 

There have been several studies recently which suggest that the medical and scientific community is also getting fed up with the hype and the assumptions that have become the bread and butter of public discussion.

When it is all said and done, the things we know to be true about weight management and weight loss are relatively simple and straight forward. They are also very effective when actually carried out. So would you like to learn from the researchers who have studied this stuff for decades, or listen to those people who have an agenda of their own to follow? Here is the first of 6 parts that explain pretty much everything we know about weight loss from a scientific angle. These points in conjunction explain how the body actually gains, loses, and maintains its weight.

1. Dieting is more effective than exercising

We often hear people say that a little exercise is the key to weight loss maybe getting off the bus a stop early and walking that last bit to work will help or that taking the stairs instead of the elevator will make a difference.  It is true, scientifically that weight loss or weight gain is a simple matter of calories in and calories out but if you were to choose one method over another, then according to Samuel Klein, MD at Washington University’s School of Medicine, it’s much more efficient to cut calories.  “Decreasing food intake is much more effective than increasing physical activity to achieve weight loss. If you want to achieve a 300 kcal energy deficit you can run in the park for 3 miles or not eat 2 ounces of potato chips.” It really is as simple as that. Scientific studies have borne this out this, testing exercise against diet and finding that in these trials participants tend to lose more weight when using dieting alone than when using exercise alone. Of course using both together would give even better results.

The problem with relying on exercise alone is that it often backfires.  There are a couple of reasons for this.  It is partly because of the effect exercise has on the hunger and appetite hormones, meaning that you feel noticeably hungrier after exercise.
Klein says “If you walk briskly for an hour and burn 400 kcal and then have a beer and a slice of pizza afterwards because the exercise made you feel hungry then you will eat more calories than you have burned.”
It may not always be beer and pizza, but people do tend to naturally compensate for the calories they expend.

David Allison, PhD  said “This is an adaptive system,” and added “For every action there’s a reaction; that’s a law couchpotatoof physics, not of biology, but it seems that it also works in biological systems. This is why we often overestimate quite radically an effect of a particular treatment.”
Allison also points out that when public health campaigns urge people to take the stairs instead of the elevator or go on a nightly stroll or, for that matter, even eat fewer calories, they are unlikely to work, since they may fail to take account of the body’s compensatory mechanisms which can totally counteract the effect.
Another big problem with trying to lose weight through exercise alone is that it is extremely tiring, and again, the body will compensate for this.
“If the exercise made you tired so that you become more sedentary the rest of the day, you might not experience any net negative energy,” says Klein.
Our basic movements throughout the day account for a large calorie burn so if you’re wiped out after exercise, and more likely to sit on the sofa afterwards then you will have lost the energy deficit you gained from your exercise.

Links:

http://www.nejm.org/doi/full/10.1056/NEJMsa1208051#t=articleTop

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