Our minds may be modern but our genes are prehistoric, which is the reason we have so much trouble losing weight! In addition to fast food, desk jobs, and inertia, there is one more thing to blame for unwanted pounds-our genome, which has apparently not caught up with the fact that we no longer live in the Stone Age: A gene known as CRTC3 decreases energy expenditure by fat cells.
Researcher Marc Montminy says, "Ideas about obesity are based on concepts of feast or famine. As humans, we developed ways of coping with famine by expressing genes like CRTC3 to slow the rate of fat burning. Individuals with these active ‘thrifty genes’ had an advantage-they could survive long periods without food." To analyze its role in fat metabolism, the researchers engineered mice lacking the CRTC3 gene and put them on diets of varying fat composition. Normal and CRTC3 gene "knockout" mice appeared similar when fed a moderate fat diet. But when fed the mouse version of the Philly cheese steak diet, only the normal mice became obese. "The CRTC3 knockout mice were leaner and protected from obesity," reports Montminy. "They also had about twice as many brown fat cells than did normal mice."
To appreciate this finding, you need to know that not all fat cells are "bad"–the problem is white fat tissue (also called WAT, for "white adipose tissue"), which serves as a fat storage depot around the midsection and hips. However, a second type of fat-known as brown fat (BAT) is ht desirable. Researcher Youngsup Song says, "Brown fat tissue burns fat that has accumulated in white fat tissue to generate heat as a way to maintain body temperature." In fact, some evidence suggests that humans with a genetic propensity to leanness have more brown fat cells than do "ample" individuals.
As desirable as that trait may seem in a "super-size me" world, those folks likely had a pretty tough time in the Paleolithic era. Why Neanderthals died out is still a mystery, but scientists have determined it wasn’t because their diet lacked variety and was overly reliant on meat. Researchers have discovered starch granules from plant food trapped in 40-thousand-year-old Neanderthal teeth, leading them to believe that Neanderthals ate a wide variety of plants and included cooked grains as part of a more sophisticated, diverse diet similar to early modern humans. Researcher Amanda Henry says, "Neanderthals are often portrayed as very backwards or primitive. Now we are beginning to understand that they had some quite advanced technologies and behaviors."
When Anne Strieber found her clothes were getting too tight she thought they had all shrunk, until she realized she had gained weight due to Type II diabetes, a genetic condition that manifests in late middle age and makes it easy to gain weight and hard to lose it. She discovered that this gene is carried by people whose ancestors lived on semi-starvation diets. To learn every MORE fascinating facts about how our genes affect our weight, download her famous diet book "What I Learned from the Fat Years!" She not only discovered WHY some of us have this gene, but what to do about it, and after three years of diet and exercise, she managed to lose 100 pounds–and YOU can too!