It’s a common occurrence: After weeks of following a successful diet plan, with weight coming off surely and steadily, the rate of decline in the numbers on the scale starts to almost imperceptibly slow…slow…. and stop.  Welcome to the weight plateau, and the frustrations that come with it.  Even worse, the weight plateau is most often followed by a tipping of the scales in the opposite direction, and the ultimate frustration as the pounds begin to add up again.  Let’s take a look at why this weight plateau happens, why weight regain most often ensues, and what we can do about it!

The short answer and hard truth of the matter is that our bodies and brains are evolutionarily wired to allow us to collect energy, and to restore energy (in the form of fat) if energy stores are depleted (as in the case of weight loss).

As nicely reviewed by Paul MacLean and colleagues, here are some of the mechanisms that may be involved (and this is not an exhaustive list!):

  •  Leptin levels drop proportionally more than fat mass.  Leptin is a hormone secreted by fat tissue, whose primary effect is to tell our brains that we feel full (it is therefore a ‘satiety’ hormone).  Because leptin is made by fat, we could expect that leptin levels drop as fat mass declines, which is true; however, the leptin levels drop lower than expected, leaving us feeling even hungrier, and giving us more drive to eat and regain weight.
  • There is a small drop in adrenaline levels and thyroid hormone levels with weight loss, which results in a lowering of metabolic rate and 24 hour calorie burn.
  • There may be a reduced biological drive to be physically active, following weight loss.
  • When we lose weight, we inevitably lose some lean body mass (muscle tissue) along with the fat. This can be minimized by increasing physical activity, but some muscle will be lost nonetheless.  People who lose proportionally more lean body mass with weight loss will have a lower 24h calorie expenditure, making it easier to hit a weight plateau.
  • Our brains do not appear to reset our appetites to account for the lower energy needs with a lower body weight.  Instead, our brains are wired to try to bring us back to the weight we were previously.  The sensitivity of our brains to hunger signals appears to be increased, and sensitivity to fullness hormones decreased, following weight loss.
  • There may be genetically ingrained processes in the muscle, liver, and fat tissue of people who have previously been obese, that work in favor of promoting weight regain, that are not present in individuals who have never been overweight (as they have never had this genetic tendency).
  • Animal studies and some human studies suggest that weight loss results in an increase in the number of fat cells, which drives weight regain.
  • A different type of bacteria inhabit the intestines of obese individuals compared to lean individuals, and these bacteria may have a different influence on our metabolism.  It is not yet well understood what happens with these bacteria after weight loss, but it is thought that they may play a role in promoting weight regain as well.

Taken together, the sum of the evidence to date suggests that that there are many factors (many of them being genetically determined) that permissively allow us to gain weight in our toxic, sedentary, easy food access environment.  Once an individual has become overweight or obese and loses weight, changes occur in their physiology which try to prevent weight from coming off, and actually promote weight regain.

These mechanisms evolved over millions of years, while the human species was fighting to survive periods of famine interspersed with periods of feast.  The trouble with the current day situation in most countries around the world, is that there is a continual feast.  Food surrounds us at every turn, and often these are foods that are poorly satiating with high caloric content to boot!

So, what can we do about this?  Well, the first step is to understand why the plateau and weight regain often happen, as this can help to decrease some of the frustration associated with it (knowledge is power!).  The good news and next step is, that these elements that promote weight regain are not insurmountable, and can often be counteracted with constant attention towards:

  • eating a more satiating (higher protein, lower carbohydrate) diet;
  • making a conscious effort to be active in daily life; and
  • programming and planning regular dedicated exercise.

Remember to speak with your doctor about what is right and safe for you, before making any changes. Also remember to view any lifestyle changes as permanent; there should be no such thing as a temporary ‘diet’.

Hopefully we will also move forward in our development of medications that may be helpful to maintain weight loss and prevent weight regain.

And, of course, it goes without say that on an individual and population level, prevention of obesity in the first place is a Number One priority.

Dr Sue Pedersen © 2011

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