It has become widely acknowledged that being in a cold environment leads to a significant increase in metabolism during both rest and exercise. Under conditions of extreme cold stress, the metabolic rate can increase up to five times during rest because shivering generates heat to maintain a stable core temperature.
When the body experiences cold temperatures, it responds by shivering, which in turn results in the burning of calories. However, is it necessary to subject oneself to freezing temperatures to achieve the benefits of artificially boosting metabolism?
Recent studies suggest that it is not necessary to undergo extreme cold exposure to stimulate metabolism. Even small decreases in ambient temperature can promote the formation of brown adipose tissue (BAT), which helps generate heat in the body by burning fat at an elevated rate. Surprisingly, BAT is a type of fat that actually burns other fats. The question then arises, how can one increase the production of this metabolically active tissue in the body?
The discovery of the beneficial effects of mild cold exposure has sparked a surge of new research studies exploring its impact on metabolism and, potentially, obesity.
The Cold Exposure Trend:
It appears that many people have become aware of individuals who are using cold exposure to achieve a leaner physique, a practice also known as "hacking." Various techniques, such as drinking large amounts of ice water, taking cold showers or baths, wearing minimal clothing in cold weather, placing ice packs on the body, setting the home thermostat to the mid-60s, and sleeping without a blanket, have gained popularity following the publication of Timothy Ferriss' book, The 4-Hour Body.
In my opinion, all the aforementioned methods seem quite unpleasant, and there is not enough scientific evidence to validate any one technique for promoting fat loss. However, the promising personal accounts from advocates such as Timothy Ferriss and Ray Cronise, a former NASA researcher, do pique curiosity. If they assert that cold exposure can enhance metabolism and promote a leaner physique, perhaps it is worth delving into the topic further.
Cold Vests: Is The Science There?
The ongoing interest in cold exposure has resulted in the creation of cold vests, which are essentially garments designed to hold ice packs. Unlike ice baths, these vests provide the ability to move around freely and participate in other activities while simultaneously lowering the body's temperature.
The cold vests are intended to be relatively comfortable as they primarily focus on areas of the body that are less sensitive to cold, such as the chest, shoulders, and upper arms. The aim is to decrease the body temperature without causing shivering. However, the question remains: do these vests truly deliver results?
I contacted Wayne Hayes, Ph.D., a NASA scientist and creator of The Cold Shoulder ice vest, to inquire if he would permit me to evaluate his product. Dr. Hayes was more than happy to comply, but cautioned that I should not anticipate immediate, dramatic results. According to him, it would take several weeks of consistent wear before I would notice any changes in my resting metabolic rate.
Scientists assess the impact of cold on metabolic rate by conducting the resting energy expenditure (REE) test. The process is relatively simple: you fast for 12 hours and avoid exercising for 24 hours, then lie in a darkened room for 20 minutes with a sizeable plastic capsule placed over your head.
During the REE test, the air you exhale is collected by the plastic capsule above your head and examined to identify the type of macronutrient that your body is using for energy at that specific moment. The data collected is combined with your physical attributes such as height, weight, age, and sex to approximate the number of calories that your body would expend if you remained in that state for a full day.
With one of Hayes' Cold Shoulders in hand, I called the university where I teach and scheduled an appointment to measure how the vest would affect my metabolism.
Test-Driving The Vest:
Two days prior to the test, I took the vest and ice packs out of the freezer and wore it over a sleeveless T-shirt. I tightened the buckles to ensure the ice remained in close contact with my body and wore the vest throughout the day with the aim of keeping it on until the ice packs thawed.I have to say that I'm not a fan of being cold, but even while the chill was noticeable, it didn't bother me. I made breakfast, took the dogs out, and answered emails, and I felt fine.
During the first hour, the ice packs had not melted, and the person started feeling colder. After two hours, the ice packs were still cold, and the individual began shivering. They attempted to warm up by putting on a sweatshirt over the vest, but it did not help much. After half an hour, they could not tolerate the cold any longer and removed the vest. However, it took the person several hours to feel warm again.
In The Lab:
After a short break, I put on the ice vest and went through the same REE test again. This time, I was instructed to wear the vest for the entire 20 minutes. At the end of the test, the researchers collected the data and compared my results with the previous test.
Unfortunately, the results were inconclusive. There was no significant increase in my metabolic rate while wearing the ice vest. It was a bit disappointing, but as Dr. Hayes had warned me, the effects of the vest on my metabolism may take several weeks of regular use to show up.
The REE test showed that wearing the Cold Shoulder vest for 20 minutes increased the estimated number of calories burned in the next 24 hours by 52. This small increase is unlikely to result in significant fat loss on its own. However, combining cold exposure with a healthy diet and regular exercise may help promote weight loss and improve overall health.
The results made sense: I was colder, so my body was working harder to maintain a stable core temperature. But the size of the results was disappointing. Yes, I could lose another 50 calories a day—all I had to do was keep the cold vest on all day.
The results made sense: I was colder, so my body was working harder to maintain a stable core temperature. But the size of the results was disappointing. Yes, I could lose another 50 calories a day—all I had to do was keep the cold vest on all day. I couldn't stand wearing it for three hours.
Consistent exposure to cold may help with weight loss, but a cold vest is not a quick or guaranteed solution. Regular exercise is still important for weight loss.
More Research That Leaves Questions:
At the end of the study, the researchers found that the men burned an additional 7% more calories per day when exposed to the cooler temperature (66 degrees F) compared to the warmer temperature (81 degrees F). This equated to an additional 100-150 calories burned per day. Furthermore, the men also had increased insulin sensitivity, indicating potential metabolic benefits from cold exposure. However, it's important to note that this was a small study with a specific population, and more research is needed to fully understand the potential benefits of cold exposure on metabolism.
That's correct. The researchers wanted to see how the men's bodies would respond to a decrease in ambient temperature without any additional insulation, such as blankets or extra clothing.
This study suggests that long-term exposure to mildly cold temperatures may have a positive impact on metabolic health and fat burning in humans. However, it's important to note that this was a small study with only five participants, and further research is needed to fully understand the effects of temperature on metabolism.
Yes, that's correct. While the cold exposure led to increased fat metabolism and other positive changes in metabolic hormones, there were no lasting changes in body composition once the temperatures returned to normal.
That's a good summary! To add to that, it's important to remember that cold exposure isn't a magic solution for weight loss, and it's not for everyone. Some people may have medical conditions that make cold exposure dangerous or uncomfortable, and others may simply not enjoy being cold. But for those who are willing and able to tolerate cold exposure, whether through a cold vest or other means, it can potentially offer some benefits. As with any weight loss method, consistency and dedication are key.