mos_glyph_hiresTonight's a very exciting night for me. I will be purposefully sleep depriving myself in order to be one of the first individual's in Joplin to see my autobiography, Man of Steel! Now I know what your thinking. If it is my autobiography why do I need to see it. Well don't get me wrong shooting the movie was a blast, but it is a whole other experience getting to see the final product. Okay, okay maybe I am not the true Clark Kent, but I sure wish I was. Superman was by far my all time favorite superhero growing up. It is probably the reason why I love being strong, it makes me feel a bit more supermanish. I don't quite have the "quicker than the speeding bullet" attribute, but I figured I would go after the one most obtainable Superman feature.

In all seriousness I think it will be well worth the sleep deprivation suffered by watching the midnight showing. It is directed by Zach Snyder, or probably more well known as the director of 300, and produced by Christopher Nolan. Yeah the same Christopher Nolan who revolutionized the Batman Saga and provided us with probably the best most recent addition to any superhero legacy. It also features Russell Crowe as Jor-El (Superman's Russell-Crowe-as-Superman-007dad), which is a reason in itself to see the movie (I mean seriously I can not be the only guy who thinks he is DA BOMB). Anyways if you can't tell I'm rather excited to see it and I give all the thanks to my lady for purchasing the tickets as a surprise (THANKS KESLEY!).

I hope more people go watch it's epicness, but until then you'll have to be entertained by this week's study. It is looking at the phenomenon of Adaptive Thermogenesis and it's ability to hinder your ability to maintain weight-loss.

Title

Weight Loss, Weight Maintenance, and Adaptive Thermogenesis

by Westerterp

published 2013 in the American Journal of Clinical Nutrition

Introduction

Adaptive thermogenesis is a phenomenon that occurs during weight loss. It describes the decrease in energy expenditure below what is predicted for the loss of a certain amount of bodyweight during any sort of dieting. Reductions below 10% of predicted resting metabolic rate have been observed and noted. This has led to some researchers to proposing that adaptive thermogenesis may be a legit reason for the failure of some individuals to achieve and maintain a reduced bodyweight through and after a diet. Proposed explanations for this phenomenon include it finding it's origin as a survival mechanism to conserve energy during periods of starvation.

In this particular study the researchers were interested in quantifying the extent of adaptive thermogenesis following a 8 week low-calorie diet. In addition the researchers wanted to observe whether or not this phenomenon was persistent after a year following the intervention.

Methods

Researchers measured adaptive thermogenesis by comparing measured and predicted resting metabolic rates. Predicted resting metabolic rate was calculated baed on levels of fat free mass and fat mass. Researchers recruited 91 healthy subjects, 69 women and 22 men, with an average BMI of 31.9. Researchers took measurements at four different times  throughout the study which included: the day before the beginning of the diet, 8 weeks after the start of the diet, 20 weeks after the beginning of the diet, and 52 weeks after the start of the diet.

The researchers measured resting metabolic rate and body composition at each measurement taking.  Researchers used Brouwer's formula to calculate each subject's resting metabolic rate and used an open circuit ventilated hood system to measurement participant's oxygen consumption and carbon dioxide production while laying supine. Body composition was calculated using Siri's 3-compartment model based on bodyweight, body volume, and total body water.

Body volume was obtained by using air displacement plethysmography with a BodPod System. Total body water was obtained by using deuterium dilution based on the Maastricht protocol. The following formula was used to calculated predicted resting metabolic rate: 0.024 x fat mass in kilograms + 0.102 x fat-free mass in kilograms + 0.85. This formula was based on a model Westerterp had designed previously and has been found to be valid for both geneders.

Finally adaptive thermogenesis was measured by dividing resting metabolic rate by predicted resting metabolic rate and a ratio is obtained.

Results

Researchers report that 8 weeks on the low calorie diet led to weight loss of 9.6 kg and after 20 weeks weight loss was 8.5 kg and at 52 weeks weight loss remained significant at 6.0 kg.

Researchers reported that measured resting metabolic rate decreased significantly from 7.31 MJ/day to 0.88 MJ/dy following the low calorie diet. It remained depressed after 20 weeks at 6.92 MJ/day and after 52 weeks at 6.97 MJ/day.

Researchers reported that predicted metabolic rate decreased significantly from 7.29 MJ/day to 6.91 MJ/day following the 8 week low calorie diet. It remained decreased after 20 weeks at 7.04 MJ/day and after 52 weeks 7.12 MJ/day.

Researchers reported that adaptive thermogenesis was 1.004 and that it decreased significantly to 0.963 after the low calorie diet. This ratio remained lower after 20 weeks at 0.983 and after 52 weeks at 0.84. Researchers also reported significant individual variation and rations were related to percentage weight loss meaning greater percentage weight loss led to greater adaptive thermogenesis. But no effects on gender were noted.

Conclusion

Researchers concluded that moderate weight loss induced by energy restriction leads to disproportional reduction in resting metabolic rate. Researchers note that this adaptive thermogenesis favors a positive energy balance during weight maintenance and may increase an individual's risk of weight regain following a diet.

Take-Away

Two big things to take away from this study. First adaptive thermogenesis is a real phenomenon and is apparent in all people who lose weight by following calorie restriction diets. In addition you will experience greater adaptive thermogenesis in greater amounts if you lose greater amounts of weight. Second this is not the ideal method to lose weight as it places you at a high risk of regaining the weight. Although the researchers don't offer thoughts on a better weight loss and maintenance strategy I will. My thoughts have to do with stem cell differentiation and that if we can place more focus on making ourselves more active and focus on a clean natural diet we can hopefully affect future stem cell differentiation to trend toward muscle cells rather than fat cells leading to higher amounts of skeletal muscle tissue, higher BMR, and more calories burned from fat while at rest.

Just do yourself a big favor and stop with the calorie restriction!

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