Dieting can be discouraging for many of us. We commit to losing weight, come up with a doable plan and begin cutting calories. Then we wait expectantly for our reward for this very hard work: a better self-image, more confidence, a trimmer figure, improved health, more energy, compliments.
But the scale barely moves.
A recent study may help explain this despairing situation. Researchers at the University of Cambridge found that a caloric “thermostat” in our brain prevents us from burning calories and expending energy when food is “scarce”—that is, we eat less.
We asked Jean-Philippe Langevin, M.D., a neurosurgeon, about why and how our bodies may be working against us when it comes to losing or controlling our weight. Dr. Langevin is director of the Restorative Neurosurgery and Deep Brain Stimulation Program at the Pacific Movement Disorders Center, located at Providence Saint John’s Health Center in Santa Monica, Calif.
How does this caloric thermostat work when our weight is relatively normal and we eat normally?
This research highlights the concept of the body as an energy store. Our weight is determined by two main factors: calorie intake and energy expenditure. In normal conditions, our brain monitors our environment continuously to make sure that we react appropriately to changes in climate and food supply. Energy expenditure is adjusted to caloric intake so that a reduction in caloric intake is associated with a reduction in energy expenditure.
What does this thermostat do when we try to lose weight?
The thermostat appears to have a specific role in maintaining weight. Energy expenditure adjusts to caloric intake in very intricate ways. When you consume fewer calories, the body reduces its energy expenditure and keeps the overall weight unchanged. If you are trying to diet to lose weight, this thermostat function will work against your plans. As you reduce your calorie intake and try to expend more energy by exercising, the thermostat region of the brain will reduce its baseline activity even more to maintain your body weight unchanged.
This thermostat could also have connections with higher order regions of the brain so that it can access important information. For example, the thermostat may not only respond to actual caloric intake but to potential future caloric intake through smell and visual information. In that sense, the thermostat could access information to help predict future caloric intake and start making adjustments in energy expenditure based on that input.
A regular thermostat at home can adjust heating and air conditioning based on ambient temperature. However, a smarter thermostat could access the internet for weather information to start adjusting ambient temperature based on predicted future temperature.
Our body thermostat gets access to a lot of information available within the brain, such as the food that we see and smell and also our plans for dieting and exercising. The current study suggests that our thermostat can use all that information in order to make adjustments to our energy expenditure, which sometimes can go against our plans.
This research suggests that a group of neurons in the brain’s hypothalamus coordinates appetite and energy expenditure. It says this function could have evolved to help humans cope with famine. Can you explain this?
Although our current society has a problem with excess weight due to high-calorie food being readily available, humanity has dealt with the opposite problem for most of its existence. As such, our bodies had to adapt to survive in conditions where food and resources were scarce.
A smart thermostat provides a clear advantage for survival. It allows the body to adapt its energy expenditure to current environmental conditions as well as current food supply, and it also allows us to adapt our expenditure to expected future supplies. In a sense, our body could start conserving energy today for a predicted upcoming famine.
You are a neurosurgeon specializing in deep brain stimulation. Does DBS hold promise in resetting the hypothalamus as a way to treat obesity?
We know from classical studies in animals that lesions in critical areas of the hypothalamus, where the thermostat is located, could lead to dramatic weight reduction. Deep brain stimulation, or DBS, utilizes small implantable electrodes to modify the function of specific brain regions. There is a lot of hope that we could use DBS to alter the function of the thermostat to adjust our energy expenditure.
Currently, people with weight problems essentially have two strategies to lose weight: reduce calorie intake and exercise more. However, the thermostat counteracts some of these efforts to normalize weight back to baseline. Using DBS, the idea would be to alter the thermostat directly to set a new lower baseline weight.
This would mean that the thermostat would always adjust energy expenditure based on the calorie intake to return to the baseline weight. Since the new weight would be set lower, the energy expenditure would be higher to burn more calories. Since DBS is adjustable, the effect on the thermostat could be adjusted to the “desired weight.”
Unfortunately, at least two small clinical trials have failed to show sustained weight reduction with DBS. Thus far, it seems that the thermostat is very resilient and discounts the influence of DBS.
Another approach would be to use DBS to reduce the body’s interest in food and generate satiety. This strategy has not been tested so far, and it looks like we will have to wait longer to see a potential obesity treatment with DBS.
If you want to lose weight, talk to your health care provider about the best approach for you. Providence offers a broad range of surgical and nonsurgical weight-loss services. Find services near you.
If you’ve had success losing weight, share your story in our comments section.