Obesity in America is a health issue we are all familiar with, and much research has been done to control and reverse it. Studies that determine these parameters are performed with groups of people from which average values are obtained, that are then applied to all people. The unfortunate result of this kind of study is that the dietary requirements and the number of calories for maintaining a certain weight determined by research may not be relevant at the individual level. Therefore, the generalized advice of the government to the public to, “keep the sugar level as low as possible,” or “the fat in our diet as low as possible,” may or may not be beneficial to all individuals. Dr. Marit Nilsen-Hamilton, Professor of Biochemistry, Biophysics and Molecular Biology at the Iowa State University, is thus developing a weight model that can ultimately reflect the state and the needs of each individual. By accumulating and analyzing data, Dr. Nilsen-Hamilton hopes to create a system that provides an accurate assessment of each person’s caloric needs, and present positive solutions to managing our body weight.

A cell biologist currently heavily involved in a number of projects that involve applications of RNA molecules, Dr. Nilsen-Hamilton has built a strong scientific background over the last 45 years that has given her a deep perspective from the molecular to the organismal level from bacteria to mammals. Recently, she embarked on a new, exciting project on weight gain and weight loss that began when she made some significant discoveries while tracking her own weight loss program. She is currently building a series of testable hypotheses from these discoveries to develop a model for weight gain and loss with the goal of helping people determine a practical dietary plan that creates solutions specific to each person’s caloric needs. Ultimately, Dr. Nilsen-Hamilton hopes to acquire data that can lead to breakthroughs that will potentially shake and shape the way we approach obesity in America.

Current areas of this new project include:

• The “Zones” of Caloric Need: One of the discoveries that Dr. Nilsen-Hamilton has made is that she can be in one of two "zones" with respect to caloric need for maintaining her weight. The difference between these zones means about 25 lb/year weight gain or loss while eating the same amount of food calories. When she is in the weight gain promoting, or the WGP, zone, she would gain ~25 lbs/year, while in the other, weight gain resistant, or WGR, zone, she would not gain anything while eating exactly the same number of calories and the same or similar foods. As the time in each zone is long, measuring out months to years, Dr. Nilsen-Hamilton studies how we are maintained in one zone or the other and how we switch between zones. Her current hypothesis is that the bacteria in our guts, or the microbiome, determine the zone and that we have a different gut population depending on which zone we are in.
• Shifting from One Zone to Another: Individuals staying in the WGR zone will likely be able to eat more without gaining weight. Dr. Nilsen-Hamilton has some grounds to believe that the sugar level in her diet determines which zone she is in, with a higher level of sugar in her diet placing her in the WGR zone, where she would want to be. The level of sugar for this zone is what has been recommended by the National Academy of Sciences. However, more recently there has been a push to lower sugar in the diet. Shifting to the lower sugar level that is now proposed by groups such as the World Health Organization is what is correlated with her being in the WGP zone where she cannot eat much without gaining weight. Dr. Nilsen-Hamilton believes that the sugar level of our diets determine which bacteria populate our guts and, moreover, whether we easily gain weight or can maintain our weight more easily without gaining.
• Caloric Needs Pertaining to Weight Gain or Weight Loss: Using herself as the model, Dr. Nilsen-Hamilton has determined her caloric needs in each zone and how they relate to weight gain or loss. Here she has the most data in the WGR zone and can now predict with more than 90% confidence how much she needs to consume to lose or gain a given amount of weight per month. The data can be represented as a straight line with a slope and an intercept, which allows her to compare her data for both zones and the lines are parallel but with different intercepts. For this part of the study she is also collecting data from one other person, whose line is parallel to hers and with a different intercept. Based on this, Dr. Nilsen-Hamilton believes that the lines for many people may be parallel, whereas the intercepts vary. Ultimately, she hopes to be able to obtain data from other individuals.
• The Role of Exercise in Determining the Zone: A fourth aspect of this research is to understand the role of exercise in determining the rate of weight loss and the zone you are in. So far, Dr. Nilsen-Hamilton’s data shows that level of exercise does not affect the rate of weight gain and loss within a zone, but that it may speed the transition between zones. In the future, she hopes to expand this research area to determine how exercise affects the transition between zones.