What is brown fat?

Definition: what is brown fat or brown adipose tissue?

Brown fat or brown adipose tissue is a specific form of fat which takes its name from its brownish color due to the presence of numerous mitochondria and a high density of blood vessels. “Brown adipose tissue is physiologically very different from so-called white fat, which is the main storage fat in the human body. Brown adipocytes contain small droplets of fat in the middle of a large quantity of mitochondria: they are therefore much less “fatty” than white ones and closer to muscle cells.” explains Dr Nys.

Unlike white fat, which stores energy, brown fat is characterized by its ability to burn fat to produce heat, a process known as thermogenesis.

Brown fat is particularly active during exposure to cold, in newborns, and during hibernation in certain animals.

White, beige, brown: What are the other types of fats?

There are three types of adipose tissue in our body, with very specific physiology and roles.

• White fat : Largely the majority, white fat is the main form of fat storage in the body. It accumulates when we consume more calories than we expend. “White adipocytes contain a large lipid vacuole and a small nucleus. They secrete adipocytokines, which are directly involved in metabolic syndrome (overweight, cholesterol, diabetes, etc.)” explains Dr. Nys. White fat represents on average 20% of body weight in a person of normal weight;
• Brown fat : The main characteristic of this fat is to burn calories to produce heat: this is called thermogenesis. It is present in large quantities in newborns, and remains in a quiescent state and in very small quantities in adults. “An adult has only a few hundred grams of brown adipose tissue, mainly located on the upper part of the body, in the neck, at the level of the subclavicular hollow, around the heart and along the spine.” describes the specialist. Brown adipocyte cells have a few droplets of fat but above all a lot of mitochondria;
• Beige grease : In anecotic quantities in the human body, beige fat, also called BRITE (for brown in white) is still poorly understood. “It is possible that it arises from the browning of white adipose tissue under the influence of certain factors such as adipokines, myokines, catecholamines, insulin or even IGF1.” explains Dr. Nys. It could therefore also be involved in thermogenesis, but to a lesser extent than brown TA.

Heat, thermoregulation in the newborn: what is the role of brown fat?

Brown fat, present in large quantities in newborns, plays an essential role in thermoregulation. “Unlike adults, newborns do not know how to shiver, which makes them dependent on this brown fat to produce heat.” explains the endocrinologist. This is called non-shivering thermogenesis.

When the baby’s body temperature drops, brown adipocytes use stored lipids to produce heat. This phenomenon is made possible thanks to a specific protein present in these cells, the uncoupling protein (UCP1).

Brown fat makes up approximately 2.5-5% of a newborn’s body weight at birth. Its quantity reaches its maximum at 3-4 weeks of life. This fat is efficiently irrigated by blood vessels, which allows the heat produced to be distributed throughout the baby’s body.

Location: Where is brown fat found in the human body?

The location of brown fat varies depending on the period of life. In infants who rely on it to keep their body temperature stable, brown fat is distributed fairly evenly, with a greater concentration around vital organs such as the heart and kidneys.

In adults, the distribution is less uniform: it is mainly found in specific areas of the body, notably around the neck, collarbones, armpits, near the spine and around the kidneys. Some studies also indicate a presence of this fat in the interscapular and thoracic region.

Diet: How to create or develop brown fat?

There are several ways to develop brown fat, including diet, which could play a major role. Certain foods actually have the ability to stimulate the production of this brown fat, in particular because of their thermogenic properties.

Among these, we find:

• THE diets high in carbohydrates and proteins could promote the development of brown fats. Indeed, certain food compounds would be capable of facilitating the transformation of white adipocytes into beige then brown: “These are conjugated fatty acids which are mainly found in dairy products and meat, arginine present in meat, fish and eggs.” specifies the nutritionist;
• Berberine : this alkaloid naturally present in the root of the Berberis aristata plant, is used to regulate blood sugar levels in cases of pre-diabetes. “It improves sugar metabolism and stimulates UCP1” specifies the nutritionist;
• Curcumin : which increases the transformation of white TA into brown TA;
• Red pepper : which contains capsaicin which is capable of increasing thermogenesis by almost 25%;
• Cinnamon : thanks to the cinnamic aldehyde it contains, it can increase the activity of brown fats;
• Guarana and green tea : these plants help activate and increase brown fats.

In addition to diet, it is possible to boost the development of brown fat by cold. “Many experiments have been carried out and have confirmed the action of cold on the activation of brown TA, but exposure to cold must be prolonged and regular, as is the case for people who live in the poles. where work in refrigerated rooms” says Dr. Nys.

Finally, regular physical activity would also promote the development of brown TA to the detriment of white TA.

It should be noted, however, that this information is based on preliminary research and additional studies are needed to confirm these effects.

How to eliminate brown fat?

Brown fat is beneficial for the body, since it helps maintain body temperature and helps fight metabolic syndrome. For these various reasons, it is not wise to try to eliminate it.

Benefits of brown fat in weight loss

Brown fat is directly involved in body metabolism and therefore indirectly in weight loss. Indeed, it is capable of burning calories to produce heat, which promotes the reduction of white adipose tissue, the main source of fat storage. “Brown fats may reduce BCAAs (branched chain amino acids), which are associated with type 2 diabetes and obesity when present in excess.” recalls Dr. Nys.

Indeed, recent studies have demonstrated that people with little or no brown adipose tissue have a reduced capacity to eliminate BCAAs from the blood, with an increased risk of contracting diabetes or obesity.

Research is currently being conducted to explore the possibility of developing treatments to increase the amount or activity of brown fat in the human body, with the aim of promoting weight loss. These treatments could offer new options for people who have difficulty losing weight through traditional methods.

Brown fat and cancer

A few studies have looked at the effects of brown fat on the development of cancers. Some of them suggest that the presence of large quantities of brown fat could be associated with a reduced risk of developing certain chronic diseases, including cancer. Indeed, the activation of brown fat could lead to the consumption of our adipose reserves, which are often linked to obesity, a risk factor for several types of cancer. Additionally, activation of brown fat by cold temperatures appears to reduce the sugar needed for the development of several types of cancers.

However, research into the relationship between brown fat and cancer is still in its early stages. More studies are needed to better understand the precise role of brown fat in cancer prevention and treatment.