"While research suggests inflammation associated with obesity may contribute to inflammatory bowel diseases such as colitis, the study results revealed a low-calorie diet may actually impair the immune system's ability to respond to infection, said Jenifer Fenton, assistant professor in the Department of Food Science and Human Nutrition.
The results are similar to the research from our department that shows consuming fewer calories make it harder to fight off the flu virus," said Fenton, referring to recent work by colleague Elizabeth Gardner. "Since this is a totally different pathogen, it amplifies the need to find out why caloric intake has such an impact on the body's ability to respond to infection.
Mice in the study were given one of three dietary treatments: a high-fat diet, a 30 percent caloric-restriction diet and a control group on an average-caloric diet. They then were treated with bacteria called H. hepaticus, which infects the colon and causes inflammation, eventually leading to tumor development. This process models the more aggressive lesions observed in human colon cancer cases.
Unexpectedly, study results suggest increased body fat induced by a high-fat diet did not influence the severity of colitis, despite changes in hormones that are known to increase with obesity and influence inflammation. In fact, researchers found calorie-restricted mice had a higher mortality rate in response to infection with H. hepaticus, dying before tumors even developed.
Previous studies suggest that obesity exacerbates colonic inflammation. Malnutrition is associated with adverse outcomes in IBD progression, exacerbating immunodeficiency, perpetuating malabsorption and increasing risk of infections. We report that moderate obesity did not influence the severity of colon inflammation in experimentally-induced colitis. Importantly, caloric restriction negatively influences survival following pathogen challenge, potentially due to an impaired immune response."
The McCombs Plan doesn't use calorie restriction due to the fact that we have found that it takes a lot of energy to detoxify the body. This research shows that calorie restriction could also weaken immune system responses. Improving digestive function will improve absorption of nutrients necessary to run the immune system and other systems of the body. The benefits of a low-calorie diet, as reported in other studies, should be looked at as benefitting someone with a digestive system that doesn't function well. Unfortunately, a low-calorie diet doesn't fix digestive imbalances, it only serves to manage the imbalance, not correct it. What we typically see with the McCombs Plan is that improving digestive function improves everything else.