Battling Obesity One Thermostat at a Time

ThermometerWinter in Wisconsin is synonymous with cold, and this year thanks to the “wobbly polar vortex” it has been really, really cold. I have been very grateful for my under-desk space heater at work and my toasty gas fireplace at home. However, according to an article currently in press in the journal Trends in Endocrinology and Metabolism (1), all that lovely toasty warmness might be working against me if I am hoping to loose weight.

Excess weight is nothing more than a positive energy balance, meaning we have taken in more calories than we have burned. The deceptively simple sounding solution for losing or maintaining weight is to take in no more calories than you will be expending. Typically this is achieved by eating less, increasing physical activity or through pharmacological interventions. However, anyone who has ever tried any of these approaches knows that there is nothing simple about them, and often times the results are disappointing or short lived.

The authors of the Trends in Endocrinology and Metabolism paper hypothesize that regular exposure to mild cold could affect our energy expenditure in a positive way. We know that shivering produces heat (shivering thermogenesis) and thus expends energy. It can increase the metabolic rate to up to five  times the resting rate (2). However, it is not comfortable and can make coordinated movements difficult. The authors focused on something close to this state, but not quite. Nonshivering thermogenesis (NST) is the cold-induced increase in heat production that is does not involve muscle activity like shivering. It occurs by activating brown adipose tissue (3–5).

Although there is great variation between individuals, most young and middle-aged people will see an increase in NST between a few percent to up to 30% when exposed to mildly cold conditions (1). The authors note that a recent study found a significant decrease in body fat content following a 6 week cold acclimation study (2 hours/day at 62.6°F [17°C]; 6).

ScaleAs many of us can probably attest, the downfall of undertaking anything that increases our body’s energy usage is that often we end up increasing our caloric intake to compensate for it. Interestingly, the authors point to a 2009 study (7) that found evidence that increased food intake did not fully compensate for this type of cold-induced thermogenesis.

Personally, I love to be warm— as evidenced by my previous comments about space heaters and gas fireplaces. However, if the benefits of cold acclimation suggested by this paper hold to be true, I think I could tolerate 2 hours a day at 62°C.


  1. Van Marken Lichtenbelt. W. et al. (2014) Cold exposure—An approach to increasing energy expenditure in humans. Trends Endrochron. Met. In Press.
  2. Jansky, L. (1998) Shivering. In Physiology and Pathophysiology of Temperature Regulation (Blattheis, C.M. ed.) World Sceintific.
  3. Cannon, B. and Nedergaard, J. (2004) Brown adipose tissue: Function and physiological significance. Physiol. Rev. 84, 277–359.
  4. Van Marken Lichtenbelt, W.D. et al. (2009) Cold-activated brown adipose tissue in health adult men. N. Engl. J. Med. 360, 1500–1508.
  5. Virtanen, K.A. et al. (2009) Functional brown adipose tissue in health adults. N. Engl. J. Med. 360, 1518–1525.
  6. Yoneshiro, T.  et al. (2013) Recruited brown adipose tissue as an antiobesity agent in humans. J. Clin. Invest. 123, 3404–3408.
  7. Cannon, B. and Nedergaard, J. (2009) Thermogenesis challenges the adipostat hypothesis for body-weight control. Proc. Nutr. Soc. 68, 401–407.

Browning of Fat as a Tool in Obesity Resistance

From Wikipedia, PET/ CT scan showing brown fat in a human.
From Wikipedia, PET/ CT scan showing brown fat in a human.

Brown fat or brown adipose tissue (BAT) is metabolically active fat. It contains mitochondria, which contribute the brown color due to their iron content. Much has been learned about brown fat in the past 5-10 years, including that there is more than one type of this adipose tissue.

Not only is there brown, but also beige fat, or as the authors of this work (Schultz T.J., et al.) call it, recruitable brown adipose tissue (rBAT). The authors contrast the two brown fats by noting that constitutive brown adipose tissue (cBAT) is embryonic in origin and is found in the interscapular region of mice. rBAT is found in white adipose tissue (WAT) and in skeletal muscle in mice.

Furthermore,  these two  brown fats are from different cellular ancestors, cBAT coming from progenitors of skeletal muscle, while rBAT is derived from a non-myogenic lineage.

Bone morphogenetic proteins (BMPs) regulate the formation and thermoregulatory activity of BAT. In this report, the authors blocked a receptor for BMP, BMPR1A, by generating a mouse model that was missing BMPR1A in all cells carrying the myogenic marker Myf5+. Continue reading “Browning of Fat as a Tool in Obesity Resistance”

In the Obesity-Diabetes Battle, Beige Fat May be a Friend

Rats have brown fat and now, beige fat as well.

In May, this writer published a blog on fat research that sounded promising in the battle against obesity and diabetes. That blog focused on research that identified the compound irisin and the ability of irisin to convert  metabolically-inactive white adipose tissue to energy-burning brown adipose tissue.

Perhaps indicative of the intensity with which research on brown fat is being pursued, Wu  et al.  published new information online last week in Cell (July 12, 2012) that there is, in fact yet another type of adipose tissue.

Announcing beige fat. The research is entitled “Beige Adipocytes Are a Distinct Type of Thermogenic Fat Cell in Mouse and Human.”

In this research, Wu et al. cloned beige fat cells, and identified unique characteristics and cell surface markers. Here are a few of their findings: Continue reading “In the Obesity-Diabetes Battle, Beige Fat May be a Friend”

The Fat You Wish You Had

A baby has brown fat. Hopefully you and I do as well.

Brown fat, white fat…isn’t all adipose tissue the same?

Previously thought of as the domain of infants and hibernating bears, brown adipose tissue has been identified in the adult human body as well.

Two papers that appeared in The New England Journal of Medicine in 2009 reported that adult humans have brown fat, found in small blobs. These blobs showed on PET/CT scans when the people scanned were in cool surroundings, with room temperatures at 61–66°F. Blobs of brown fat show up on PET scans because these scans identify areas in the body where cells are more actively using glucose (1–2).
Continue reading “The Fat You Wish You Had”