High Sugar and Fat Diet May Change Intestinal Bacteria Leading to Weight Gain

How might a high sugar and fat diet, as in some cakes, cookies, and bread products give you a giant belly? If the usual colony of bacteria dramatically changes due to your high fat and high sugar diet, you probably will gain weight.

Or at least that's what happened to mice in a new study of how diet rapidly changes gut bacteria in ways that affect weight gain. On the other hand, you either have the genes for sugar and fat to go from lips to hips. Or you have the genes to put the weight on your abdomen. Also see the weight loss surgery channel article, "Bad diets can alter stomach bacteria for the worse."

Bacteria currently being called "human gut flora" may prove to be an active factor in America's obesity trend. Scientists tested this idea on mice, inserting the human bacteria into their intestines.

When they fed the mice a high-fat and high-sugar diet, they saw an immediate change in their internal structure. The mice quickly showed an increase in body fat and the kinds of bacteria that are linked to becoming obese. Video plays below.

You might also check out the Los Angeles Times article, "Bad diet may alter bacteria to encourage weight gain." Or check out the article, "Bad Diets Can Alter Stomach Bacteria For The Worse |Weight Loss."

According to the study, "The Effect of Diet on the Human Gut Microbiome: A Metagenomic Analysis in Humanized Gnotobiotic Mice," in the journal, Science Translational Medicine, 11 November 2009, if you eat a high fat and high sugar diet, the composition of the bacteria in your guts will change in ways that gaining weight becomes easier. It would also be harder to lose weight. However, the research has been done using mice.

According to the study, it only took 24 hours for the bacteria to change. This rapid change in the specific bacteria amazed the researchers at Washington University, St. Louis, Missouri. The issue is that the bacteria in your intestines plays a key role in how you gain or lose weight, if humans react in the same way as the mice did in that study.

In addition to a change in your intestinal bacteria (or at least in the mouse's gut bacteria) you have genetic factors playing a role in how fast you gain weight on a high sugar and high fat diet. Gaining or losing weight also is affected by various types of physical activities, your environment, and what you eat.

What the study focused on showed that bacteria in the gut plays a key role in gaining weight. The study can lead to new ways to prevent obesity.

What the Study Emphasized

According to the abstract of the study, "Diet and nutritional status are among the most important modifiable determinants of human health. The nutritional value of food is influenced in part by a person's gut microbial community (microbiota) and its component genes (microbiome).

"Unraveling the interrelations among diet, the structure and operations of the gut microbiota, and nutrient and energy harvest is confounded by variations in human environmental exposures, microbial ecology, and genotype. To help overcome these problems, we created a well-defined, representative animal model of the human gut ecosystem by transplanting fresh or frozen adult human fecal microbial communities into germ-free C57BL/6J mice.

"Culture-independent metagenomic analysis of the temporal, spatial, and intergenerational patterns of bacterial colonization showed that these humanized mice were stably and heritably colonized and reproduced much of the bacterial diversity of the donor's microbiota.

"Switching from a low-fat, plant polysaccharide-rich diet to a high-fat, high-sugar "Western" diet shifted the structure of the microbiota within a single day, changed the representation of metabolic pathways in the microbiome, and altered microbiome gene expression.

"Reciprocal transplants involving various combinations of donor and recipient diets revealed that colonization history influences the initial structure of the microbial community but that these effects can be rapidly altered by diet.

"Humanized mice fed the Western diet have increased adiposity; this trait is transmissible via microbiota transplantation. Humanized gnotobiotic mice will be useful for conducting proof-of-principle "clinical trials" that test the effects of environmental and genetic factors on the gut microbiota and host physiology."

The big picture in this study is that a poor diet may alter intestinal bacteria to encourage weight gain, but also what kicks in are genetics, environment, and physical activities. With a high fat and high sugar diet, scientists know that sugar is fed to rats to raise their blood pressure because salt affects the salt-sensitive rat, but sugar is an all-around weight enhancer. The high fat diet works if your genetics is such that your genes don't remove the fats. But which fats?

The moral of the story is if you eat a low sugar diet, it helps. But if you have metabolic syndrome, maybe you need a certain amount of specific types of fats. That's why talking with a health care professional helps you to tailor your food to your body's requirements. Some people need more of certain types of fats than others. And as for sugar, you'll get enough in fresh fruits.