April 2, 2009
New nutrition professor hungry for insight into appetite
Hollis untangling knot of questions surrounding eating habits
James Hollis, assistant professor of food science and human nutrition, has had a life-long interest in his research area, appetite and weight regulation. |
By
Scott Schrage
As obesity and fad diets grip larger and larger portions of the United States, Iowa State University is turning to a Brit to help piece together the puzzle of the human appetite.
James Hollis, newly hired assistant professor of food science and human nutrition, began examining the processes of appetite and weight regulation while earning his doctorate at Oxford Brookes University in England.
“I think I’ve always had a fascination with food,” Hollis said. “I’ve always been interested in weight regulation – what makes people eat, what makes them choose the foods that they choose. I’m [also] really fascinated by how different foods alter our appetite, and by consequence, our body weight.”
Hollis believes that while the modern food industry is responsible for some of the public’s health problems, it also has the opportunity to remedy them.
“We can only do that by looking at what food science can contribute to nutrition,” said Hollis. “How can we change the parameters of food processing or food ingredient use to impact human health? A lot of these changes are only going to elicit subtle changes in health, but because we’re exposed to food so much [and] for so long … these could really manifest themselves in quite profound changes in a society’s health.”
Hollis noted that there are many factors – physiological, genetic and environmental – that potentially affect appetite and weight gain. One of the physiological factors is gastric distension, or the amount of time a food resides in the stomach before it is broken down and absorbed by the body. Hollis is currently building a gut model in order to simulate and test the effects of food hardness, texture and viscosity on the speed of digestion.
“If we don’t understand the factors of food and how they drive appetite, then we’ve got no chance of manipulating them,” he said. “The work at the moment is to look at … which of these factors are important; if we manipulate them, do they then change appetite?”
One of Hollis’ recent studies focused on how the chewing of food can influence people’s appetites. He found that the more often subjects chewed peanuts, the more satiated they felt. Hollis is investigating whether differences in food fragment size and calorie absorption may be responsible.
Though he’s making important strides in understanding how human appetite functions, Hollis stressed that there is much yet to be discovered. Among the current mysteries of the appetite is perhaps the most fundamental of all: its function.
“We don’t know what the true goal of appetite is – whether it’s to maintain a certain body weight or whether it’s to maximize food intake in times of plenty,” said Hollis, summarizing the two primary theories in the current debate.
Extremely high rates of obesity – including 25 to 30 percent of the American population, according to Hollis – have led him and other researchers to question the “set point” weight theory. The evolutionary perspective, on the other hand, may help explain the trend.
“We’re hardwired, from an evolutionary standpoint … [to] want to eat as much as possible – [to] lay down the fat stores because we know that the food supply isn’t stable,” Hollis said. “That brings up an interesting question to me, because one of the things that is often put forward to help people maintain weight is, ‘Listen to your body. If it says you’re full, stop eating.’ But if your body is trying to fool you, in a sense … then if you listen to that, it’s just driving you on to become obese.”
Hollis’ hope for stemming the tide of obesity comes not only from educating the public, but from looking beyond the traditional nature versus nurture debate.
“It’s a false dichotomy that people come up with: Is it biology [or] is it environment? It’s the two of them acting in concert together,” he said. “You could have a biological system that strongly predisposes people to be obese, but if there’s not an environment that provides enough food for [it], they won’t become obese.”
While he works to untangle the complex knot of scientific questions critical to public health, Hollis is also reacquainting himself with the American education system. Though he spent the last two years teaching in England and received his entire education there, three years of postdoctorate work at Purdue University taught him much about the differences between the two countries. Still, he realizes he has a good deal yet to learn.
“The systems are quite different,” he said. “I’m going to be exposed to different classes and different teaching methods that I haven’t used before, and try to incorporate new thinking into [my] teaching.”
Despite the numerous changes, Hollis will continue to emphasize what he sees as a universal lesson – one that he has learned while exploring the depths of his field.
“As a professor, you realize that you don’t know anything for certain – you just have varying degrees of certainty,” he said. “There are always questions. There’s always room for interpretation and analysis.”
