[AnnRue]

http://www.latimes.com/features/heal...,4770405.story

latimes.com
Health

Bacteria in intestines play role in weight gain, study finds
A high-fat, high-sugar diet alters the composition of bacteria in the gut, making it easier to gain weight and harder to lose it.

By Thomas H. Maugh II

November 12, 2009

A high-fat, high-sugar diet does more than pump calories into your body. It also alters the composition of bacteria in your intestines, making it easier to gain weight and harder to lose it, research in mice suggests. And the changeover can happen in as little as 24 hours, according to a report Wednesday in the new journal Science Translational Medicine.

Many factors play a role in the propensity to gain weight, including genetics, physical activity and the environment, as well as food choices. But a growing body of evidence, much of it accumulated by Dr. Jeffrey I. Gordon of Washington University in St. Louis, shows that bacteria in the gut also play a key role.

Humans need such bacteria to help convert otherwise indigestible foods into digestible form.

Ninety percent of the bacteria fall into two major divisions, or phyla: the Firmicutes and the Bacteroidetes. Previous research had shown that obese mice had higher levels of Firmicutes, and lean ones had more Bacteroidetes.

Analyzing the genomes of the bacteria, Gordon and graduate student Peter Turnbaugh concluded that the Firmicutes were more efficient at digesting food that the body can't.

Animals that have a higher proportion of Firmicutes convert a higher proportion of food into calories that can be absorbed by the body, making it easier to gain weight.

When the researchers transferred bacteria from obese mice into so-called gnotobiotic mice, which were raised in a sterile environment and had no bacteria in their guts, the mice gained more weight than did those receiving a similar amount of bacteria from lean mice, even though they were fed the same diet.

Gordon and Turnbaugh found that they could transfer bacteria from human intestines into gnotobiotic mice, which were fed a low-fat, plant-rich diet in the weeks before the bacteria were transplanted and for a month afterward.

After the bacteria were transplanted from a lean human donor, the colonies in the mice had a high proportion of Bacteroidetes and a low proportion of Firmicutes. But within 24 hours after the mice were switched to a high-sugar, high-fat diet, the proportions of the two phyla were reversed.

With time, the mice also grew fatter than their littermates who did not receive the human bacteria.

[AnnRue]

I was interested in the study for a few reasons. Maybe this rings a bell with you.

1. I have said for years that either a. I can't count calories right, or b. I need less calories than what doctors say. I have been a diet expert since I was 10. How is it possible that I have been messing up? This seems to say it is possible that I am NOT messing up. That I am getting more calories per day than I thought I was.

2. I think this expertly explains how I can gain weight hand over fist if I do cheat. For example, say I have a piece of cake at work to celebrate a birthday. Then come home and have my regular meal -say pasta. Presume the high sugar of the cake wipes my bacteria and I eat dinner that I thought was 400, but really is 600. Going forward knowing this, I can make sure to eat low calorie foods - such as salad. If I know I had cake.

3. I have never believed in "starvation mode" but admittedly as you go on in a diet you are more likely to have a handful of candy or an ice cream later as you get closer to your goal. You can only go cold turkey for so long. You think, well this isn't going to hurt me, I only ate 1000 cals today. Yet you get to this point you just can't lose at all. What if there are three factors going on here... a. your metabolism does slow down; slight cheating wipes your bacteria and also increases your calorie count so that you are just about even with the calories burned. Doesn't this explain how people that are starving / anorexics die and don't hit starvation mode ever?

4. I have always said that exercise just doesn't seem to do what I think it is going to do. I can work out for 1 hour - supposedly lose 400 cals... think I had a deficit of 700 cals. But not lose weight -- for a month or more. Then you get discouraged. But what if, your deficit was only 300 cals because of this bacteria thing?

I am not saying that diet and exercise have to be thrown out the window. But it is just one more tool and the never ending puzzle of weight loss. For me it has given me hope to get back on the wagon again. I haven't had sugar for a week (amazing for me) and made me more likely to seek out veggies than choose bread. When before I couldn't quite see why one choice or the other would be bad. I used to grab a handful of m&ms at work and just count it as 100 cals and think that was it, but what if that handful of m&m's really was 400 cals in the damage it did to me. Really keeps me from reaching in, ya know.

[Xan]

Thanks for posting that -- I know I FEEL better after about a day of cutting out sugar and bread. Maybe it's not the carbs? Maybe it's the bacteria? That is one of the problems with weight loss, and nutrition generally. There are so many studies looking at one variable, but not at a whole range of variables.

What I want to know is, how do you kill off those Firmicutes!

[AnnRue]

Originally Posted by Xan

What I want to know is, how do you kill off those Firmicutes!

At one point I know studies came out where they were not sure if the firmicutes were with us from birth so maybe you can't. Maybe you can just reduce them by eating better.

I think it is just more evidence that losing weight can be extremely complex.

[kaplods]

Originally Posted by AnnRue

Doesn't this explain how people that are starving / anorexics die and don't hit starvation mode ever?

Actually starving folks and anorexics DO hit starvation mode. Starvation mode does not prevent weight loss and death from starvation, it only slows down the process. Anorexics and famine victims are often able to survive on astonishingly few calories, for quite prolonged periods of time - but it catches up with them. In order to sustain themselves longer on fewer calories, body processes slows down and fatigue increases. Famine victims and anorexics eventually become bed-ridden (and you don't need as many calories to sustain yourself, when you're bed-ridden, but you also are at greater risk for bedsores and other issues).

Often anorexics and famine victims die from complications of starvation, before they die from starvation. Their immune system stops functioning correctly, for example, and they may die of a bacterial or viral infection that they otherwise would have been able to fight off.