Think you know how to lose weight? Not so fast…

If you’re one of the 1.4 billion adults who are overweight or obese, chances are you’ve looked for ways to trim the waistline. According to a new review published the New England Journal of Medicine, some of the things we have all heard as keys to weight loss are not only unfounded, they are also untrue.

A team of researchers from across the globe scoured the academic literature to determine what popular ideas about diet, obesity, and weight loss were myths, which were presumptions, and which were facts–things that actually carried the weight of scientific evidence behind them. The results were surprising.

The researchers started by debunking seven weight loss “myths”. These were defined as beliefs about weight loss taken as true despite contradictory scientific evidence. Among them:

  • Small, sustained changes resulted in large, long-term changes in weight
  • Realistic goals were necessary because dieters become frustrated and give up otherwise
  • Breast feeding is protective against obesity later in life

These changes, the research team asserted, are simply not true. In debunking these myths, there are studies showing how individual variability affects changes in body composition, and therefore, rates of loss, how ambitious goals are sometimes associated with better outcomes, and there is no correlation between breast-feeding and obesity in adulthood. However, the researchers did not discount other potentially important benefits of breastfeeding for both mother and infant.

Next on the block were presumptions about weight loss. These were defined to be things that were widely held to be true, but had neither been proven or disproven in the literature, or, at best, studies yielded inconclusive results. Among these presumptions were:

  • Eating breakfast is protective against obesity
  • Eating more fruits and vegetables, regardless of other behavioural or lifestyle changes, leads to weight loss or preventing weight gain
  • Snacking contributes to weight gain

These, they said, showed mixed results. The breakfast studies showed no effect to whether or not an individual was obese or gained weight; the participants weight loss was more dependent on which group they were assigned to (eaters vs. skippers) in comparison to their usual habits. The fruit/veg and snacking presumptions simply had no merit–while consumption of fruits and vegetables is healthy and provides important minerals, neither habit was indicative of weight loss.

Despite the debunking going on, the researchers were also able to dig up a few facts regarding weight loss, and these were perhaps the most enlightening to me, as they went against a few things I had always been taught.  Among the facts:

  • While genetics plays a large role, your genes do not determine your destiny.
  • For overweight children, school programs are not enough. Healthy eating and exercise habits must also occur at home.
  • Some pharmaceutical agents can help an individual lose weight, so long as those agents are used.

And, my favourite:

“Obesity is perhaps best conceptualised as a chronic condition, requiring ongoing management to maintain long-term weight loss.”

The upshot of all this is that, despite what the media, your neighbour, or perhaps even a doctor might tell you, there is not one way to go about losing weight, maintaining weight loss, or even preventing weight gain. The things that work for an individual may not work for a population. In short, we all have to muddle through and make changes that fit us, fit our lives, and are effective.

The full article is available for free at the NEJM website.

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