What effect does temperature have on our body weight?

Cold prevents overweight and metabolic diseases in offspring

Temperatures in our environment have a significant impact on our metabolism and the risk of certain diseases. This also applies across the generations, according to a recent study. For example, cold causes more brown adipose tissue in offspring before procreation and protects against obesity and metabolic diseases, ETHZ (ETHZ) reports the study results. Information transmitters are spermatozoa.

ETHZ scientists have been able to prove in mice that the outside temperature at the time of conception has a great influence on the offspring. An international team of researchers led by Professor Christian Wolfrum of ETH Zurich was able to demonstrate that a central course was already defined before conception. If the father stays cold before being conceived, the offspring will have more active brown adipose tissue. In other words, an environmental influence to which the father is exposed is transferred to his offspring, report the researchers. A similar relationship is also evident in humans.

Brown adipose tissue with many benefits

Those who have a lot of brown adipose tissue are lucky: this tissue, which is found in some people under the tongue, at the level of the clavicle and spine, using Exploitant excess energy, the study authors explain. The more tissue you have and the more active it is, the lower the risk of being overweight or developing metabolic diseases. The research team came to this conclusion in the mouse surveys.

Time of onset with profound influence

A relationship between design temperature and brown fat is also found in humans, according to the researchers. The researchers analyzed CT images of 8,400 adult patients and found that individuals who had a birthday from July to November (and therefore conceived in winter) had significantly more active brown adipose tissue than those born between January and June (and years )

Outdoor temperatures affecting fathers

In the mouse studies, animals were kept either at a moderate temperature (23 degrees Celsius) or at a cool temperature (8 degrees Celsius) and could naturally reproduce. "The analyzes of the offspring showed that the temperature of the mother before and after conception had no influence on the brown adipose tissue of the offspring, but on that of the fathers"; the scientists report. Their study results were published in the journal "Nature Medicine".

Prevention of Obesity and Metabolic Disorders

Offspring of males living in a cool environment for several days prior to conception had a more active brown adipose tissue than males living at temperate temperatures, explain Researchers. In addition, the offspring of men who were in the cold, better overweight (with diet high in fat less weight gain) and were protected against metabolic diseases.

Epigenetic changes in sperm

According to ETHZ, researchers were able to use in vitro fertilization and sperm analysis to show that information about the temperature of the father's house is transmitted to the descendants by epigenetic imprinting of the spermatozoa. This is a change in the structure that forms certain chemical markers (methylations) on the genetic material. It has long been known that environmental influences can alter the epigenetic profile of spermatozoa. For the first time, however, scientists have been able to prove that ambient temperature also leads to epigenetic changes, reports ETHZ.

Best Protection Against the Cold

Experts explain that the production of body heat including the burning of energy is in the foreground. Thus, mice with more brown adipose tissue are able to better regulate their body temperature at low temperatures. According to Professor Christian Wolfrum, they could "be protected from the icy cold, which could explain why this epigenetic mechanism has prevailed in evolutionary history". In addition, observations in mice and in humans are consistent with previous observations. have a lot of brown fat, say the researchers.

The effects of temperatures in our living environment

The authors of the study point out yet another context. So, there are already studies that show a relationship between temperature and obesity. In addition, the average indoor temperature has increased over the last few decades, at least in the United States. This could also have effects on body fat and the risk of metabolic diseases. To what extent, for example, couples involved in family planning should now focus on cold weather remains an open question.

Help cool down before conception?

According to the researchers, it would probably not be helpful if the man stood in front of him active cooling (eg swimming in the cold lake). "Before we can give such advice, we need to look more closely at the context in humans," says Professor Wolfrum. Probably for an epigenetic impression but a longer exposure to the cold is necessary. According to the head of the study, "jumping into cold water or sitting on a block of ice may not be enough". Other studies comparing the epigenetic nature of human sperm in summer and winter are already underway, according to the researchers. , (fp, pm)