Fat and obesity

Some of recent news regarding fat and obesity.

"Carbon emissions fuelled by high rates of obesity"
Researchers from the London School of Hygiene and Tropical Medicine compared a population of 1 billion lean people, with weight distributions equivalent to a country such as Vietnam, with 1 billion people from richer countries, such as the US, where about 40% of the population is classified obese. They found that the fatter population needed 19% more food energy for its energy requirements, and additionally, greater car use by the overweight.
The study was published in the International Journal of Epidemiology. "Population fatness has an environmental impact," says Phil Edwards, one of the authors.

Original paper: "Population adiposity and climate change"


"Obesity: Be cool, lose weight"
"To lose weight, would you rather diet, exercise or subject yourself to cool temperatures? The last choice is not such an odd one, as adult humans have brown fat tissue that burns calories in response to cold."
A review in the News & Views of the Nature journal says that.

Fat is mainly stored in two types of adipose tissue: white and brown. White adipose tissue (WAT) stores fat as lipid droplets, whereas the brown adipose tissue (BAT) burn it to produce heat and regulate body temperature.
It has been thought that only small mammals and newborn humans have BAT. However, three recent studies published in the New England Journal of Medicine identified BAT in adult humans, primarily behind the muscles of the lower neck and collarbone as well as along the spine of the chest and abdomen.
BAT can be activated in response to various stimuli including exposure to cold. It seems that the process is more prominent in the young and lean than in the old and obese, and in women rather than in men.
Recently, it was revealed that brown and white fat cells have different stem-cell origins (Nature 454, 961-967, 2008). A transcriptional regulator called PRDM16 controls a bi-directional switch in cell fate between skeletal myoblasts and brown fat cells. Additionally, BMP7 was identified that promotes brown adipocyte differentiation and thermogenesis (Nature 454, 1000-1004, 2008).
"Drugs that mimic its action might also be effective anti-obesity agents", says the review.

Original papers:
"Cold-Activated Brown Adipose Tissue in Healthy Men"
"Identification and Importance of Brown Adipose Tissue in Adult Humans"
"Functional Brown Adipose Tissue in Healthy Adults"


"Dietary Fats Trigger Long-term Memory Formation"
"Having strong memories of that rich, delicious dessert you ate last night? If so, you shouldn't feel like a glutton. It's only natural."

Researchers from the University of California, Irvine (UCI) reported that eating fat-rich foods triggers the formation of long-term memories of that activity. They found that administering oleoylethanolamide (OAE), a fatty acid derivate, to rodents improved memory retention in two different tests. The team previously reported that OAE regulates feeding by inducing satiety through activation of the nuclear receptor PPAR-alpha and reduces the body weight gain (Nature 425, 90-93, 2003). The actions of OEA were mimicked by PPAR-alpha agonists and abolished in mutant mice lacking PPAR-alpha.
Daniele Piomelli, the team leader, said that the OEA's memory-enhancing activity seems to have been an important evolutionary tool for early humans and other mammals by helping mammals remember where and when they have eaten a fatty meal.

Original paper: "Fat-induced satiety factor oleoylethanolamide enhances memory consolidation."


MEGMILK "Metabo-free yogurt"
In Japanese, "metabo" is a synonym for "fat" or "obesity". Of course the word derived from "metabolism", and was associated with "metabolic syndrome". So "metabo-free" does not mean no metabolism: this product contains no trehalose, which is need for cryptobiosis, but no fat.