One of the most challenging health crises facing the United States today is the rising rate of obesity. Nowadays, it’s well-known that two out of every three Americans are either overweight or obese. The deleterious effect of obesity on health has been studied, but little headway has been made on actually reducing obesity on a nationwide scale, despite the best efforts of many Americans who try to diet and lose weight each year. Recently, researchers have been looking into the reasons why weight reduction is so difficult for so many people.
Why Is It So Difficult to Lose Weight?
Researchers have discovered that significant weight gain can lead to subtle changes in the body that may make it more difficult for people to lose weight. For example, studies have found that obese patients may experience decreased taste sensitivity. Researchers hypothesize that people with a dulled sense of taste might then be tempted to seek out foods that are richer in sugar, salt, and fat, or to consume more to achieve the same level of sensation that someone who is a recommended weight might feel. Andrew Kaufman, a fourth-year graduate student in Robin Dando’s Lab, Food Science, is currently searching for the biological mechanisms responsible for this reduced sense of taste.
As an undergraduate, Kaufman studied biochemistry and states that he has always been interested “by food and how people experience food in different ways.” While deciding on a graduate school, he chose to attend Cornell based on the strength of the Food Science program here. Kaufman was the first graduate student in the Dando lab, which has since expanded to explore various influences on taste perception, such as pregnancy and emotional affect.
Kaufman is interested in building a more comprehensive understanding of obesity and why it can be so difficult to lose weight. For many overweight or obese Americans, shedding pounds might not be just a simple matter of willpower. What’s more, Kaufman hopes that his research has the potential to identify markers that could predict whether this loss of taste buds will occur and how it might be prevented. This could be especially important for patients who have taste disorders, such as those who have undergone chemotherapy.
Taste buds are tiny clusters of cells present in the tongue that allow people to perceive the five tastes: salty, sweet, sour, bitter, and umami. Each taste bud contains three different types of cells that are responsible for taste, and each of these cell types regenerate at different rates. Using mouse models, Kaufman compares lean mice models to those that have been fed a high fat diet for eight weeks, eventually gaining 50 to 70 percent of their original body weight. This would be similar to comparisons between a “normal” weight and a moderately obese person. On a small section of each mouse’s tongue, Kaufman stains the taste buds for a number of cellular markers. This method allows for the quantification of specific types of cells, developmental markers, and the presence of dead cells.
Kaufman has found that heavier mice have fewer taste buds present in their tongues. In addition, he has observed slower taste bud cell regeneration in these heavier mice, which may be a reason for why they have fewer cells. Furthermore, when using transgenic mice that are unable to gain weight, the same reduction in the number of taste buds is not observed. Kaufman hypothesizes that it is the weight gain specifically and not the high fat diet that leads to this dysfunction. Promisingly, if the heavier mice are switched back to a lean diet, there appears to be a reversal of this effect.
For many overweight or obese Americans, shedding pounds might not be just a simple matter of willpower.
Obesity and Genetics
Besides researching the structure of taste buds in mice, Kaufman is interested in the effect of obesity on genes and gene expression. One of the major problems that obesity causes is inflammation of tissues, which can lead to DNA damage. Kaufman is exploring what changes in gene expression might be caused by excess fat tissue and whether this leads to the decreased number of taste buds present in heavier mice.
The process of extracting mRNA from tongue tissue involves injecting the tissue with enzymes and peeling the epithelium off the tongue. Kaufman then carries out the delicate and difficult task of gathering individual taste buds by using a small pipette, a process that he says took him months to master. From these taste buds, he can compare the expression profiles of heavier versus leaner mice and even see which genes are expressed at what times.
When he’s not in the lab working on his research, Kaufman enjoys tennis, squash and watching independent movies at Cinemapolis. Despite having to adjust initially from life in New York City, he states that living in Ithaca has helped him focus on his graduate work.