Photo: Courtesy Of UC Berkeley / UC Berkeley
These mice ate the same high-fat diet in a UC Berkeley study, but the sense of smell was removed for the one on the right, helping it stay slim.
These mice ate the same high-fat diet in a UC Berkeley study, but the sense of smell was removed for the one on the right, helping it stay slim.
Real or not? Drink the ultimate San Francisco martini, made with a locally made vodka diluted with fog-derived water.
Real or not? Drink the ultimate San Francisco martini, made with a locally made vodka diluted with fog-derived water.
Real or not? If you're tired of traditional burritos, try a new fusion kind that turns a sushi roll into, well, a large burrito-sized sushi roll. Sheets of seaweed serve as the outer layer, with pieces of tuna sushi inside.
Real or not? If you're tired of traditional burritos, try a new fusion kind that turns a sushi roll into, well, a large burrito-sized sushi roll. Sheets of seaweed serve as the outer layer, with pieces of tuna
Real or not? In a nod to the city's gold mining history, try a decadent, $100 gold pizza the pie comes with white truffles, 24-month aged prosciutto, mushrooms and more. Oh! And there's gold flakes on top.
Real or not? In a nod to the city's gold mining history, try a decadent, $100 gold pizza the pie comes with white truffles, 24-month aged prosciutto, mushrooms and more. Oh! And there's gold flakes on top.
Fake. Although delicious-sounding, no such thing exists. Yet.
Fake. Although delicious-sounding, no such thing exists. Yet.
Real or not? Boring IPAs, step aside: Liven things up with a taco-inspired beer. With this IPA, drinkers will notice a tropical aroma, followed by notes of traditional Mexican seasonings, such as cumin, coriander and cilantro.
Real or not? Boring IPAs, step aside: Liven things up with a taco-inspired beer. With this IPA, drinkers will notice a tropical aroma, followed by notes of traditional Mexican seasonings, such as cumin,
Real: Cellarmaker Brewing Co. first brewed this beer in 2013, but brought back "Taco Hands" (as it's called) in time for Cinco de Mayo last year.
Real: Cellarmaker Brewing Co. first brewed this beer in 2013, but brought back "Taco Hands" (as it's called) in time for Cinco de Mayo last year.
Real or not? Craftsman & Wolves, makers of the "The Rebel Within" a brunchtastic muffin complete with egg inside is now going to serve its muffin sans egg.
Real or not? Craftsman & Wolves, makers of the "The Rebel Within" a brunchtastic muffin complete with egg inside is now going to serve its muffin sans egg.
Real or not? Sweet ice cream is for the unadventurous. Step outside the box with a prosciutto-flavored ice cream that is a cold and savory treat.
Real or not? Sweet ice cream is for the unadventurous. Step outside the box with a prosciutto-flavored ice cream that is a cold and savory treat.
Real or not? This is most likely the ultimate pork dish. If you're a fan, try a wood-oven roasted pig head that is cooked until its skin is crispy, complete with gold leaf melted on the tip of the snout.
Real or not? This is most likely the ultimate pork dish. If you're a fan, try a wood-oven roasted pig head that is cooked until its skin is crispy, complete with gold leaf melted on the tip of the snout.
Real or not? If you're a fan of both coffee and wine, not have both at once? Wine-infused coffee beans are the next frontier for those looking for a drink that infuses both worlds in a single cup.
Real or not? If you're a fan of both coffee and wine, not have both at once? Wine-infused coffee beans are the next frontier for those looking for a drink that infuses both worlds in a single cup.
Real or not? This is certainly not your normal slice of Kraft American cheese: Along with its normal goat cheese bits, is a specialty cheese that incorporates vegetable ash into the mix.
Real or not? This is certainly not your normal slice of Kraft American cheese: Along with its normal goat cheese bits, is a specialty cheese that incorporates vegetable ash into the mix.
Real or not? In a bid to rescue any dented or ugly leftover vegetables from the Ferry Plaza Farmer's Market, this business gathers them and creates a protein-laden power bar for customers.
Real or not? In a bid to rescue any dented or ugly leftover vegetables from the Ferry Plaza Farmer's Market, this business gathers them and creates a protein-laden power bar for customers.
Fake. Although the fictional power bar does fulfill a number of foodie credos (Locally sourced? Check. Nutritious? Check.), this one is false.
Fake. Although the fictional power bar does fulfill a number of foodie credos (Locally sourced? Check. Nutritious? Check.), this one is false.
Real or not? If you're a beer fan in the know, you know to look out for Girl Scout Cookie beers. This line of beers is based on five different cookies from the Girl Scout line, including Samoa, Do-Si-Dos, Thin Mint, Trefoil and Tagalongs.
Real or not? If you're a beer fan in the know, you know to look out for Girl Scout Cookie beers. This line of beers is based on five different cookies from the Girl Scout line, including Samoa, Do-Si-Dos, Thin
Real or not? Vegetarians can finally move away from the portobello mushroom "burger" and finally have a burger that is veggie, but has all the meaty burger qualities that carnivores love. This new veggie burger "bleeds," sears and develops a burger "crust" to the patty all while helping to alleviate the environmental impact of meat production.
Real or not? Vegetarians can finally move away from the portobello mushroom "burger" and finally have a burger that is veggie, but has all the meaty burger qualities that carnivores love. This new veggie burger
Just smelling food can make you fat, UC Berkeley study says
On the bustling streets of San Francisco, people can sense whats grilling, baking and frying in restaurants from North Beach to Noe Valley without even looking at the menus, as myriad cuisines serve up a smorgasbord of aromas for the nostrils.
But what most foodies and waist-watchers strolling by dont realize is that just smelling burgers, pizza, sushi, falafel or any of the other sweet and savory offerings could be causing them to gain weight.
A study by UC Berkeley researchers found that a sense of smell can influence the brains decision to burn fat or store it in the body or a least the bodies of mice.
Researchers Andrew Dillin and Celine Riera studied three groups of mice normal mice, super-smellers and ones without a sense of smell and saw a direct correlation between their ability to smell and how much weight they gained from a high-fat, Burger King diet, Dillin said.
Each mouse ate the same amount of food, but those with a super sense of smell gained the most weight.
The normal mice ballooned, too up to 100 percent from the weight they were when the research started.
But the mice who couldnt smell anything gained only 10 percent of their weight. Obese mice who had their sense of smell wiped out slimmed down to the size of normal counterparts without a change in diet.
Riera said the study, which was published this month in the journal Cell Metabolism, reveals that outside influences such as smell can affect the brains functions related to appetite and metabolism.
Other studies have shown that olfactory systems, the organs and lobes related to smell, can influence things like sexual behavior or fertility, but this study isnt related to internal functions or hormones, said Riera, a former UC Berkeley postdoctoral fellow now at Cedars-Sinai Medical Center in Los Angeles.
In the context of food and appetite, this is really novel, she said.
Using the studys methods in humans could be possible.
After eating, a persons sense of smell decreases. So, if a person was eating with a lessened sense of smell, the brain could be tricked into thinking its already been fed and choose to burn the calories instead of store them, Riera said.
People struggling with obesity could have their sense of smell wiped out or temporarily reduced to help them control cravings and burn calories and fat faster.
But there are risks.
People that dont have a sense of smell can get depressed, because the sense of smell is very important for behavior, Riera said. They lose all pleasure of eating.
People who lose their sense of smell from aging, injury or diseases like Parkinsons can also struggle with keeping weight on.
The mice in the study who lost their sense of smell also saw a significant increase in the hormone noradrenaline a stress response from the nervous system that can lead to a heart attack if levels are too high.
Eliminating a humans sense of smell would be a radical step, said Dillin, an expert in stem cell research. But it could also be an option for obese people who are considering such weight-reduction alternatives as stomach stapling or gastric-band surgery, even with the potential for high levels of noradrenaline.
In both humans and mice, decreasing or wiping out the sense of smell is only temporary. In the study, researchers injected a toxin that destroyed olfactory neurons in the nose, but they avoided the stem cells which allowed the neurons to grow back in three to eight weeks.
To use the method in a human population, scientists would need to know how many of the olfactory neurons to destroy and how often, Dillin said.
Because once the sense of smell comes back, the weight could also return.
Maybe once a year you block your sense of smell for a while and then you lose the weight from the year and do it all over again, Dillin said. We dont know yet. Theres a lot we still need to do.
Alison Graham is a San Francisco Chronicle staff writer. Email: agraham@sfchronicle.com Twitter: @alisonkgraham
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Just smelling food can make you fat, UC Berkeley study says - SFGate