Wednesday, May 31, 2006

Women in food insecure households are more likely to gain weight

Food insecurity appears to be related to weight gain in women. Researchers had already noticed that women in food insecure households were more likely to be overweight. The new contribution in a study by Jerusha Peterman and myself, recently in the Journal of Nutrition, is to use nationally representative data to measure the change in weight over the same 12 month period for which food security status is measured.

We found that women in fully food secure households had a comparatively low probability of gaining 10 lbs or more during the year, and women with intermediate levels of food insecurity (such as "food insecurity without hunger") had the highest frequency of gaining 10 lbs or more. Women with the most serious evidence of food insecurity with hunger were back to having a comparatively low risk of gaining 10 lbs or more.

What could be going on? Perhaps an involuntary "boom and bust" food cycle due to food insecurity tricks the body's metabolism into retaining calories when they are available. Or perhaps the same resource cycle simply provokes people to eat bad inexpensive food when resources are scarce. Or perhaps both food insecurity and weight gain were caused by some other factor, which we were not sufficiently clever to measure. Because it looks at weight change, rather than just cross-sectional comparisons across people, the study increases the circumstantial evidence that food insecurity leads to weight gain, but it still falls short of proving causation.

We don't know why the same pattern didn't show up for men.

I got interested in this topic after studying the "food stamp cycle" in my dissertation and later research some years ago. It turns out that a large fraction of people's benefits are spent in the first few days after they are received. I think it would be worthwhile to study policy options such as delivering benefits twice monthly, to see if this approach improves the program's effectiveness in promoting both food security and good nutrition, without deterring participation by imposing undue hardship on program participants.

This research also may call into question whether "losing weight" should be one of the 18 items on the federal government's official food security survey. It happens that USDA's Economic Research Service is currently seeking public comment about the content of that survey, with a deadline of June 16 for comment submission (.pdf). I will share my thoughts in a future post, in addition to sending the comments to ERS, but if you are thinking of sending comments, see first the recent National Academies report on the topic for a bunch of context.

The Journal of Nutrition paper has received a good deal of press in the past few days. My school's public relations office described the article in a "policy point." The research was summarized in a brief by Sena Desai Gopal in the Boston Globe (scroll past the first article here) and an article by Amy Norton on Reuters.

Jerusha is giving a brief presentation of the paper at the annual meeting of the American Agricultural Economics Association (AAEA), as part of a "track" of sessions sponsored by the Food Safety and Nutrition Section, on Monday July 24 in Long Beach, CA. The session (.pdf), which includes other papers on food security measurement, including a briefing about the National Academies Report, is titled, "Hunger in America: A moment of reflection on U.S. food security measurement."

3 comments:

Barbara said...

Park, as someone who grew up in Appalachia, I think I might have some insight into this.

One is biology. Women are made to put on fat in times of plenty in case of famine, because women make babies. Having a little calories put aside in the form of fat, leads to higher-birthweight babies if you are pregnant during a famine or a drought. That is why women carry more bodyfat than men. Men's metabolisms are not geared as much toward putting on fat as women's.

So that is why you see it in women, not men.

You also have to look at how the women grew up--if they grew up in households where food insecurity was high, that may have set their metabolisms to be overly "grabby" with calories in regards to turning them into fat. The body has a memory, and if it is hungry over an extended period in youth or young adulthood--it never seems to forget, and will be more prone to putting on and holding onto fat as a survival mechanism. (I am saying this because as a young adult, I was very anorexic. Now that I am not actively anorexic, my body does not like to lose any weight, even if I exercise, even if I eat sensibly. I have hit a set size and cannot go below it without either a big illness or medical intervention. I have also seen this pattern among other anorexics and bulimics, and among women who spent time in an involuntary hunger/famine situation.)

Another factor is emotional--stress tends to make women eat more, and generally of cheap, bad things to eat, like junk food. I have seen this over and over among women, and not as much among men.

Another thing is the fear of wasting food in an impoverished household.

I saw this growing up time and time again--when women scrape the dishes to wash them, if the kids left anything on the plate, she eats it, because she cannot bear wasting food. And when she eats it, even if she barely ate dinner, she eats enough calories to make her gain weight.

A final factor is the prevalance of soda-drinking among poor populations. This is another thing I grew up seeing--a lot of my poorer friends did not drink milk at every meal like I did, but drank instead, soda. Mom and Dad did, too--it is cheap and tastes good, and quenches thirst. As you and I know, it is also full of empty calories. If one drinks a two litre's worth of soda a day, the calorie hit is astronomical, and some folks drink as much as two two-litres per day.

And it makes them huge.

When I stopped drinking soda, I lost four dress sizes. Four.

So--these are the kinds of things that researchers should be looking at--the differences between male and female metabolism, family history of the women--did they grow up in food insecure households, they need to look at patterns of stress eating, and eating food left on plates, and finally, the patterns of soda drinking.

I think that keys to that puzzle lay right there.

Do no nutritional researchers come from poor backgrounds? (Maybe they should team up with anthropologists and sociologists, too--they are used to observing cultural behaviors in the context of the culture. That might help.)

Mark said...

If they're gaining weight, the answer is simple: they're just eating more calories.

Since fast food is calorie dense, it's easy to do if most of your meals are from fast food chains.

And once the pattern is established, it tends to be self-sustaining. If you're around other fat people, you tend to get fat and stay fat. There're no role models for healthy eating, and there's no stigma involved in overeating.

Anon said...

I work as a remote public health nutritionist in outback Australia and see very high rates of obesity amongst the adult Aboriginal population, and very poor growth rates of children, in an environment of food (read "fruit and vegetable") insecurity and welfare dependancy. Ironically, our nutrition policy says that we should offer conventional (diet and exercise) weight loss programs to the same population.

My belief is that this approach only serves to blame the victim and that we should work to solve the problem of underutilisation of vegetables and fruit and welfare dependancy before we can expect success in weight loss programs.