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science nutrition blog

science nutrition <strong>blog</strong>

First, allow me to apologize to any offended by the title. Too often, a vulgar phrase is used to draw attention to a vacuous and poorly written advertorial. Hopefully, instead you will find a compelling argument to support a simple but effective change to promote fat burning. Rather than being something that costs time and money, it is effortless and may even save you some cash. In fact, it could even save world resources and reduce “global warming.” Al Gore would approve of this method … I probably just offended even more people.

There has been a long history of “thermogenics” used in the pursuit of promoting and accelerating fat loss by increasing overall calorie burning and fatty acid oxidation (burning fat for calories) to generate heat instead of ATP (cellular energy). It is akin to a home builder burning lumber for heat instead of using it to frame a house— wasting material to dispose of excess. In fact, the term “calorie” is derived from the energy required to raise one gram of water one degree Celsius. It is a measure of heat in its purest form, though chemists use the lower case “c” to refer to one gram of water and the upper case “C” to refer to one kilogram (or a liter) of water being heated. Nutritionists are always referring to “C”-alories, even when they write “c”-alories.

Thermogenic drugs and supplements function by forcing the body to generate heat inappropriately. It is similar to a teenager revving the engine at the stoplight— it may give him a thrill, but it is just wasting gas. Similarly, most thermogenic agents were based upon beta-adrenergic drugs that interact with the same receptor(s) as adrenalin. These are sometimes referred to as stimulants as many also provide a “buzz,” especially if they are adulterated with an amphetamine-class drug. These types of “supplements” quickly become best-sellers, but the adulterated products are illegal, and may cause serious health issues; it could even lead to the loss of a job due to a positive drug screen.1

Now, think for a moment. These drugs promote fat loss by signaling to the body that it needs to raise its core temperature. The chemical signal is being sent throughout the body indiscriminately, not to specific tissues, as the “sensors” have not detected anything amiss about the environment. If it is not cold, your brain is not going to tell you to waste precious calories (our bodies are designed to store, not waste energy stores). So the thermogenic stimulant attaches to every type of tissue that has the right receptors, and signal other effects as well. This is why the heart rate, blood pressure and alertness elevate, tremors begin and the mood may elevate or deteriorate.2 Your body thinks it is in a stressful environment with higher doses.

Thermogenic Supplements Work

The positive argument is that thermogenic drugs/supplement (e.g., ephedrine/caffeine) work, and the effect can be maximized through increased drug intake; the downside is that adverse effects arise, especially with doses at the high end of the therapeutic range and beyond. Further, dependence or a “gateway” effect may occur in people susceptible to drug dependency. Also, many other drugs and supplements may interact with these agents, amplifying the risk. Adderall and Ritalin are commonly abused among students and young professionals, and thyroid medication may alter the effect, as well as caffeine from other sources, and sleep deprivation can all impact certain risks.
What if instead of being a liar to your body, you simply put it in an environment that required it to increase the core body temperature appropriately? When the body signals for greater heat production, in a mildly cool environment, it does so through nerve signaling. This uses the neurotransmitter norepinephrine (closely related to adrenal hormone epinephrine, which is adrenalin) that is released from nerve endings located directly at the appropriate tissues (e.g., brown fat, skeletal muscle, blood vessels). It is only when the environment gets so cold that greater heat is needed that “adrenalin” kicks in, resulting in shivering. In fact, there is a clear differentiation between “shivering thermogenesis” and “non-shivering thermogenesis.” This is the premise of several papers published during the last decade.

In a cool environment, the body is capable of generating heat without the need for increased movement. Again, as the ambient temperature drops further, shivering and muscular activity are induced to increase thermogenesis. Think of a time you were outside, and as the evening wore on, you began to feel uncomfortably chilled. To that point, you were able to compensate without any conscious thought because your brain was monitoring the core temperature and inducing specialized tissue to produce additional heat to keep the vital organs at body temperature. Blood flow to the skin and extremities is also constricted, resulting in cold hands; some people’s lips and fingernails turn blue-ish before they start shivering. If you continued to sit outside, you likely found yourself shivering slightly. In frigid winter conditions, shivering can become excessive and near-immediate when the wind and weather combine to, well, freeze your ass off.

The Process of Thermogenesis

Briefly, the process of thermogenesis involves metabolically active tissues with fat stores increasing the rate at which the glucose (sugar) and fats are broken down, transported into the mitochondria (the furnaces of the cell), and burned as calories. Rather than using the caloric energy to create ATP (the energy molecule in the cell), the process is disconnected by a process called “uncoupling.” Uncoupling is a common path for numerous thermogenic agents, including T3 (thyroid hormone), clenbuterol, DNP and bile acids.3-5 Uncoupling interferes with muscle growth and physical performance if it exceeds physiologically acceptable limits. The ultra-potent uncoupler DNP has resulted in many deaths from hyperthermia and organ damage.4
An interesting finding reported in a 2012 study demonstrated that beta-adrenergic agonists (adrenalin-like stimulants) did not activate brown fat activity, despite being capable of elevating body temperature.6 This suggests that beta-agonist drugs may affect skeletal muscle or other tissues with greater impact compared to brown fat tissue, as well as promote fat release from adipocytes (fat cells). It is also worth noting that lean people are more sensitive to brown fat activation with ephedrine, whereas the obese are resistant.7 This may be an effect of a metabolic state that interferes with the signaling of brown fat, or the insulating effect of subcutaneous fat.

Cold-induced thermogenesis does not require freezing conditions to induce uncoupling in brown fat, skeletal muscle or recently described “beige fat.”8 It can be activated in a room controlled at 60 degrees Fahrenheit, even as mild as 66°F.9 In fact, lowering the temperature of a room from 80°F to 66°F resulted in adult men with functioning brown fat (some people don't have this ability) burning an additional 410 calories daily.10 This same temperature change was later reported to be capable of increasing energy expenditure by 5.3 percent, a more modest but still significant effect.9 A drop from 66°F to 60°F was even more effective at activating brown fat with an increase in resting daily energy expenditure of 17 percent, based upon imaging and metabolic studies, suggesting an even greater number of calories could be “burned” without effort.11 At 60°F, some people become uncomfortable or bundle up in clothes, defeating the purpose of cooling the room. Bear in mind, about one-third of people have insufficient brown fat to respond to cold with brown fat thermogenesis.

Thermoneutral Environments and Cold Exposure

The evidence is clear that subtle changes in the environment can lead to pronounced effects on calorie burning if maintained throughout the day and night. This has led some to incorporate the concept of promoting health and weight loss by reducing the ambient temperature in buildings. What this means is that architects and policymakers are looking at reducing the recommended room temperature in offices and homes to the temperature range noted to still be comfortable when thermogenesis is active, (around 66°F). It has been noted that the “thermoneutral” environment people expect results in stable conditions that obviate any need to expend any calories to maintain body temperature (thermogenesis). Therefore, one might expect health benefits, weight loss and reduced energy bills (during cold weather months) by allowing buildings to be maintained at a comfortable temperature that requires people to generate a portion of the zonal heat via thermogenesis.12
An interesting paper from the Netherlands discussing cold exposure advocated this approach, as well as a practice called temperature training. Citing research that showed a reduction in body fat in people who spent two hours per day in an environment controlled at 62°F, and noting that six hours per day spent at 59°F was uncomfortable and produced a shivering thermogenesis, the researchers recommended an ideal range of 64-66°F.12,13 This range has been noted to induce brown fat thermogenesis and increase metabolism, boosting daily calorie burning by 100-400 calories.

As noted, the environment has to generally be cool enough to induce thermogenesis, without interfering with daily activities, work or comfort. There are other efforts that can be made to maximize “comfortable cooling.” It has been shown that compared to a warm drink, the ingestion of water at room temperature can increase metabolism slightly, but significantly for a short period— roughly a 2 percent increase for 20 minutes. If the drink is chilled in the refrigerator, the effect can be increased another percent for the same brief period.14 Now, some may think that chasing a few calories here and there is frivolous, but long-term success in fat loss is the culmination of many small changes, not single sweaty marathons on a treadmill or some cabbage soup-like diet.

Perhaps a Nice Warm Bath?

Just dropping the thermostat a few degrees may help drop a few pounds, and a glass of cold water every now and then may certainly help nudge those calories down as well. What about making the effort even more relaxing? Perhaps a nice warm bath? Immersing yourself in a warm bath causes blood to drive into the core due to the increased pressure on the skin blood vessels from the weight of the water compared to the weight of air. This increases the delivery of blood to the heart, resulting in the release of a hormone called “atrial natriuretic peptide” (ANP).15 In addition to increasing diuresis (urine production, which is why people have to get out the pool to pee so frequently— or at least we hope they get out of the pool before peeing)— ANP also stimulates fat loss.16 You don't have to stay in the bath long, either— as little as 15 minutes will do.
Of course, many people desire the ultimate fat-loss experience, and seek out the coldest tolerable conditions to promote fat loss. Certainly, young wrestlers have sat in the cold storage freezers at a restaurant during work breaks; “polar plunges” into frigid waters are televised at certain times; even camping in the winter in a tent as insulated as a Ziploc bag has been done. These would all be effective, but are of such an extreme as to be uncomfortable for most, and therefore not followed consistently. With small changes, it is consistency that is the key.

Another practice common among younger people is sitting in a hot tub, and then diving into a cold pool for the intense shock that occurs. Though it is unquestionable that the body reacts violently to the extreme change in temperature, the effect is immediate and stressful, rather than mild and conditioning. Adrenalin surges, as does cortisol, in response to the physical stress. Blood flow is constricted, but only until the person re-enters the hot tub, resulting in “swinging” changes in blood pressure, peripheral resistance, vagal/sympathetic tone and other effects. It can be dangerous to the elderly or those with cardiac disease, including unknown rhythm disorders. Instead, after a cool shower, allow your body to air dry. Evaporation has the same effect as sweating— it cools the body. However, the water being evaporated comes from a body that has not performed intense physical labor, so the cooling has to be countered by thermogenesis. Depending upon the temperature of the room, it may be all non-shivering thermogenesis, or if it is a cold room, shivering may ensue.

Following the mention of sweating, a brief comment on heat loss may aid in prolonging non-shivering thermogenesis. In normal conditions, heat is lost via conductive or radiant loss, meaning you either warm something you are in contact with, or the heat just radiates off your body like an asphalt road in the summer (those mirage waves you see). It helps to reduce as much insulating material as you can. Of course, the purpose of this is to remove body fat, but shaving body hair, wearing you hair short or shaving your head, wearing light clothing, using thin bed sheets at night and utilizing a fan can all promote this mild, but continuous means of burning extra calories.

It may sound simple, but it is the equivalent of almost an hour of walking on a treadmill daily, and has positive metabolic benefits. It may take some “temperature training,” and it appears that some people just don’t have brown fat. That said, find something that costs less or is safer in the realm of fat-loss aids and techniques.


1. Cohen PA, Travis JC, et al. A methamphetamine analog (N,alpha-diethyl-phenylethylamine) identified in a mainstream dietary supplement. Drug Test Anal. 2013 Oct 14. [E-pub, ahead of print]
2. Haller CA, Jacob P 3rd, et al. Enhanced stimulant and metabolic effects of combined ephedrine and caffeine. Clin Pharmacol Ther 2004;75:259-73.
3. Lee JY, Takahashi N, et al. Triiodothyronine induces UCP-1 expression and mitochondrial biogenesis in human adipocytes. Am J Physiol Cell Physiol 2012;302:C463-72.
4. Grundlingh J, Dargan PI, et al. 2,4-dinitrophenol (DNP): a weight loss agent with significant acute toxicity and risk of death. J Med Toxicol 2011;7:205-12.
5. Puigserver P, Picó C, et al. Effect of selective beta-adrenoceptor stimulation on UCP synthesis in primary cultures of brown adipocytes. Mol Cell Endocrinol 1996;117:7-16.
6. Vosselman MJ, van der Lans AA, et al. Systemic beta-adrenergic stimulation of thermogenesis is not accompanied by brown adipose tissue activity in humans. Diabetes 2012;61:3106-13.
7. Carey AL, Formosa MF, et al. Ephedrine activates brown adipose tissue in lean but not obese humans. Diabetologia 2013;56:147-55.