When I ask someone in my office what diet(s) have they tried in the past, the common response is “What haven’t I tried” or “You name it, I’ve tried it”.  Their concern is that they have “permanently damaged” their metabolism. I hear statements like, I’m hear to “fix my broken metabolism” or “all the dieting has ruined my metabolism”. So is this true? Can yo-yo dieting permanently damage one’s metabolism?

As usual, lets look to the science!

 In a study conducted by Wadden and colleagues (1992) at the University of Pennsylvania School of Medicine, they found the answer to this question.

 They took 50 obese females with a mean age of 40 years old and weight and height of 224lbs and  5”2’, respectively. They all consumed 1200 calories at the start of the study and were then randomly assigned to three very low calorie diet groups for 11 weeks.

 These groups were:

 1.      420 calories

2.      660 calories

3.      800 calories.

 After the 11 weeks, each participant consumed a balanced diet of 1000-1500 calories for 5 weeks.

Here is what they found: They found that weight cycling had no effect on metabolism. Moreover, they also found no increases in depression, disordered eating, or percentage of weight as fat.

This means that weight cycling will not metabolically impact the success of a future dieting. That’s good news. However, we really don’t want to weight cycle for other reasons. We want to lose weight and keep it off.  So if the metabolism isn’t permanently damaged with weight cycling, why is it so hard to keep the weight off?

I am only going to address one issue here (and there are a multitude of factors that make weight management difficult). The metabolism will always match the circumstance. When I gain weight my metabolism becomes inefficient, on the other hand when I lose weight my metabolism become efficient. Inefficiency in an energy usage perspective means I use more energy for any given task, including maintaining my body in homeostasis. The opposite is true for efficiency; my body requires less energy to maintain itself. So when we lose weight we require less energy over time, when we gain weight, our bodies will require more energy to maintain. This is why we plateau as we gain weight and we plateau when we lose weight. This is normal, and why diets can be so ineffective. As coaches, that is our job. To help you understand the science of the body but also give you the tools to help manage the circumstances. Lean into the scientific truth, equip yourself with the understanding of what your body does under certain circumstances, and get the tools to help manage these changes. When we lose weight there will be things that will help manage. One of these is exercise. Exercise is one of the best weight management tools we have, not a great weight loser, but a great weight manager.

Research Wadden, T. A, Bartlett, S., Letizia, K.A., Foster, G.D., Stunkard, A.J., and Conill, A. Relationship of dieting history to resting metabolic rate, body composition, eating behaviour, and subsequent weight loss. American Society for Clinical Nutrition, 1992; 56:203S-8S.

This stretch is important for those who sit for the majority of their day.

The goal is to feel it in the front of the hip. If needed, place a soft cushion under the knee. If you need a deeper stretch, lift the back leg up onto a step.

How To: Hip Flexor Stretch

1) With the leg you want to stretch, start with one knee on the ground.

2) Pull your pelvis up and back.

3) Push your hips forward until a stretch in the front of the leg is felt.

4) Hold for 30 seconds, then switch sides.

See the photo below to see a Group 23 physiotherapist performing the exercise.