Uneven gains. The mice with an immunity gene eliminated the gain less weight than normal mice, and their livers ( insert ) Pack on less unsightly fat.
Shian-Huey Chiang et al., Cell 138 (September 4, 09) © 09 Elsevier Inc.
when we eat may be just as important as what we eat. A new study shows that mice that eat when they should be sleeping gain more weight than mice that eat at normal hours. Another study highlights why we pack on the pounds in the first place. These studies are translated into human therapies that help beat obesity remains to be seen, but they give scientists clues about the myriad of factors to consider.
Observations of workers overnight showed that eating at night disrupts the metabolism and hormones that signal that we are satiated. But nobody had done controlled studies on this connection so far. Biologist Fred Turek of Northwestern University in Evanston, Illinois, and graduate student Deanna Arble examined the link between a diet high in fat and eat what day mouse hour. A group of six nocturnal control mice ate their pellets (60% fat calories, mainly lard) overnight. Another group of six ate the same meal during the day, Turek said, disrupting their circadian rhythm -. Cycle 24 hours normal body
After 6 weeks, mice unscheduled weighs almost 20% more than the controls, Turek and Arble report today obesity supporting the idea that the consumption of calories when you should sleep is harmful. Turek and Arble recognize that disrupted mice ate some more and were a little slower, but the differences could not account for all of the weight gain.
In the second study, another team of researchers studied the link between weight and the immune system. Hundreds of genes seem to affect the accumulation of fat, but helps to protect against infection might help us lose weight with little effort, biochemist Alan Saltiel of the University of Michigan, Ann Arbor, and colleagues suggest today cell . Researchers tested adding weight capacity of a protein called IKKε, which is linked to obesity, diabetes and chronic inflammation of low. For 3 months, the team introduced six missing IKKε mouse genes of a high-fat diet chow.
Because the main job of IKKε is immune defense team Saltiel did not expect to find differences in weight between the mice and knockout controls. But the knockout mice do not earn much less. Best of all, the circumference of the animals added was less harmful to their overall health. "The knockout mice do not gain much weight, but also do not get diabetes, do not get insulin resistance, and do not get fat accumulation in the liver," said Saltiel, who contribute all as a result of the health problems associated with the excess weight. Saltiel IKKε called "a drug target particularly attractive for the treatment of metabolic diseases."
Tom Maniatis molecular biologist at Harvard University, praised the study but remains skeptical about any drug that inhibits IKKε. He helped develop the mice used in the experiment and notes that they are vulnerable to influenza. He suspected that removing IKKε can help people with diabetes or obesity, "but the first time that swine flu arrives here."
The researchers are also enthusiastic about the paper circadian rhythm. Frank Scheer, a neuroscientist at Harvard who studies sleep was hit that "you can see something happening [to the disrupted mice] in the first week already. This is consistent with human studies where we found changes in only 3 days. "
Together, the documents suggest that there is no simple answer to why people gain weight. Said Turek, "It is clearly not only the calories in calories compared to the outside."
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