Let’s Talk About Intentional Weight Loss and Evidence-Based Medicine

You are a doctor. You are trying to get through a busy clinic day when there is a knock at your office door. It is a pharmaceutical rep. Before you can say anything, he lets himself in, saying, “I’ll only take up a minute of your time, but I just have to tell you about this exciting new weight loss drug. It’s 95% effective at treating obesity in adults.” Sounds good right? Oo, he’s giving away a free pocket knife with the drug’s logo on it. Maybe you do have a minute to spare. You know you have some questions about the study that got this new drug approved.

You start by asking how much weight the study participants lost on average. Turns out it’s about 10% of their body weight in the first year. So women weighing 250 pounds at the start of the study weighed, on average, 225 pounds after a year.

Well ok, so it’s not a cure for obesity, but it still sounds useful. Everyone’s always telling you how small weight loss can have a dramatic effect on health. And besides if you took the drug for five years you could lose 50% of your body weight, right?

Well…the rep tugs at his collar…not exactly. By the end of the second year, people in the study had started to regain the weight. At the end of the study subjects taking the drug weighed, on average, about six pounds less than the control group. In fact, by the end of year five, less than half the subjects had sustained their modest weight loss. Somewhere between 20-80% of subjects (depending on who you counted and how long they stayed in the study) had gained even more weight than they lost.

Ouch. So in the long run this drug could actually hurt more people than it helps? That can’t be right, can it? Still, that’s still a lot of people who are able to sustain weight loss in the long term. Given the terrible consequences of obesity, maybe a small chance at weight loss is worth the risk. Well, actually, now that you think of it, what are the other risks? That is, what are the side effects?

The rep clears his throat and begins to mumble a list. Depression, worsened self-esteem, difficulty concentrating, constant hunger, obsession with food, increased risk of eating disorders. Also bone loss.

But the side effects were rare, right? Was the drug well tolerated? The rep scratches the back of his neck. Actually not so rare. Actually about half of people assigned to take the drug dropped out of the study and no one’s sure what happened to them.

Whoa. That doesn’t sound harmless at all. Still, if it’s a choice between depression and obesity, you know most of your patients will choose depression. So which of your patients might be good candidates for this new drug?  It’s a new treatment, so maybe all of your patients should try it, just in case it works.

But then the rep starts shuffling his feet. He mutters something and you realize that this supposedly new drug is just a reformulation of a drug that has been around for a long, long time. In fact, it’s been around so long that people accept it as dogma that it works, despite its lack of evidence base. It’s extremely popular. In fact, now that you think about it, you don’t have very many obese patients who haven’t tried this drug in one form or another, on and off for most of their lives. Does it really makes sense to make them try the same drug that has failed them so many times?

But you’re not ready to give up yet. What about the control group in this drug study? What about the poor souls who did not even get to try the drug, who were just abandoned to their disease? I mean, whatever the drug’s effects, it can’t be worse than just continuing to live with obesity, can it?

The rep is ready for this. There was a control group in this trial, he is excited to tell you. He is excited, because it turns out the numerous prior studies of this drug rarely have a well-chosen control group, they just compare different formulations of the same drug if they even have a comparison group. But this control group was given no weight loss intervention at all! Instead of being encouraged to lose weight, they were just counseled on their “health” (the rep uses air quotes for this word, as though people like that could even have health). They were given mental health interventions, including learning how to read their body’s cues for hunger and satiety, and support for body image issues. They were encouraged and supported in physical activity, and taught to find ways to move their body that felt good and were sustainable. The rep is giggling now.

So it sounds like the control group must have gained a lot more weight? He stops giggling. Actually no. And how did the two groups compare in terms of other metabolic outcomes like blood pressure and cholesterol? The control group did better. And mental health outcomes? The control group did way better (though the rep whispers But who cares, it’s not like mental health is really health.) And did half of this group drop out too? No, they mostly stayed.

You politely escort the pharmaceutical rep out, thanking him for the pocket knife and accepting his card. He has given you a lot to think about.

Will you recommend the new drug? To anyone? Only to the few people that have never tried it before? How many times should you require your patients to try and fail with this drug before you recommend they stop?

Well friends, by now you see where I’m going with this: the drug in this story is not really a drug invented by some sleazy big pharma boogeyman. It is every weight loss intervention there is. It is Weight Watchers, Jenny Craig, Nutrisystem, the Atkins Diet, the Paleo Diet, the Blood Type Diet, the French Woman’s Diet, the Aerobic Housecleaning Lifestyle, the Grapefruit Diet, the Sugar-Free Diet, the Ice Cream Diet, a sensible low fat diet, and MyPyramid. It is Orlistat (slower regain but more fecal incontinence) and all the other weight loss drugs. It is gastric bypass surgery and lap bands (those probably produce slower regain, but no one really knows because the quality of the evidence is so poor, though it clearly involves greater risk of being hospitalized for things that happen when someone surgically remodels your stomach). The diets, the pills, the surgeries, they all work the same–for the vast majority there will be temporary weight loss followed by weight regain, often at serious cost to mental and physical health.

Please remember this when some recommendation comes out suggesting “treat the weight first” and that all other health problems will have to take a back seat. Remember this when academics are slap-fighting about whether BMI is linked to mortality. None of it actually matters at all to the patients you have today, because existing weight loss interventions don’t work. Even with outcomes for which weight loss could be beneficial, the benefit will be temporary if and when the weight comes back. Quickly or slowly it will come back for all but a very few. The best most people can expect for their pain and suffering is to be about five to ten pounds lighter, and those are the minority for whom the treatment succeeds. It doesn’t matter how big a problem you think obesity is, and it doesn’t matter whether or not you’re right about it, because we do not have any tool that will make obesity go away.

Like the villain in this story, there are a lot of people and a lot of companies who make money off of the promise of weight loss. It’s a great business model; the more the intervention fails, the more money people pour into it. These people and companies have a vested interest in perpetuating the lie that anyone can and should become thin. But medicine doesn’t have to be a part of it.

To any reader who would like an overview of these issues in scientific language rather than in the form of a short story, I highly recommend this review article by Linda Bacon.

Update 1/24/2015: It’s been great to see how much interest this post has generated, and I hope that it will start a lot of productive conversations. Hello and welcome to everyone that’s new here. Out of more than 1,000 visitors that have stopped by in the past 24 hours, only one person has felt the need to leave hostile comments, which I have since deleted. However in the interest of keeping the dialogue constructive I don’t think I can continue to leave comments unmoderated, and since I can’t commit to moderating them in a timely manner I have disabled comments. Thank you to everyone who is contributing to a civil discourse around these complex issues.