The depth of penetration is estimated to be 2-3 inches. The IRRH:skin reaction is exothermic. The release of local heat from the infrared radiant heat is believed to be therapeutic by some health experts.
The Sauna HeaterMost sauna heaters today are steel-coated. Steel coating seems to be an older technology that directs the heat source but requires more time to warm up, operates at higher temperatures, and uses more energy to reach the level necessary for deep tissue penetration.
The new infrared saunas are ceramic-coated and tend to be more efficient, producing the same heat necessary in a shorter time to penetrate tissue as the steel-coated originals.
IRRH and Weight Loss?This is from an ad in the Dallas Voice, a local newspaper.
"Perspiring is part of the complex thermoregulatory process of the body that increases the heart rate, cardiac output, and metabolic rate. The process requires a large amount of energy and reduces excess moisture, salt and subcutaneous fat. Fat becomes water soluble at 110 degrees (F) and the body sweats out fats and toxins."
Wow. That's some weird sweat. Let's start by reviewing the thermoregulatory process referenced in the ad. We want to find out if infrared radiant heat stimulates the thermoregulatory process AND if that alone is enough to cause significant weight loss.
For our purposes, significant weight loss will be defined as FAT LOSS. Remember, a real diet or weight loss program forces your body to utilize fat stores. That's it. Weight loss by any other mechanism isn't healthy and should not be considered as an option to lose weight.
The Thermoregulatory ProcessThis is a very complex topic. Many factors are involved in keeping the human body temperature around 37 degrees Celsius (98f). The hypothalamus (part of the brain) regulates the entire process with the exception of initial heat loss mechanisms.
Sweating, rapid breathing, and increased blood flow to the extremities are examples of the early responses that occur as body temperature increases.
The question is can these mechanisms cause weight loss by "burning" fat. Cedric Bryant, chief exercise physiologist for the American Council on Exercise, says no.
"The amount you sweat is indicative of your body's ability to maintain its normal body temperature. You sweat when your body starts to store heat so you can experience cooling via evaporation of that sweat. So it doesn't correlate to how much energy, or calories, is being expended. You are not going to utilize stored fat simply by raising body temperature...it's not going to happen."
It makes sense too. Fat stores are slow to respond, even when a negative energy balance is achieved. Fat metabolism runs on a long term scale. You will not burn fat in this manner.
What you are burning are carbohydrates. Joe King, writer for the Journal of Hyperplasia Research, said, "Evaporation accounts for increases in total oxygen uptake, which causes the working muscles to utilize more glycogen." Glycogen is the stored form of glucose, the main carbohydrate used for energy.
A sales representative for a business selling infrared saunas said, "The heart receives a workout similar to a 6-mile run in a 20-30 minute IRRH sauna session and the body perspires the same amount as a 6-mile run. He may be right, but it's not fat that you're losing, it's carbohydrates.
ConclusionInfrared radiant heat saunas are not a weight loss option.
By Michael A. Smith, MD