The Case of the Fitbit-Defying Metabolism, Part II
The Mystery of Metabolism and Mood
Since I got a Fitbit Flex for my birthday a month ago, my attention has been so singularly fixed on the data it provides (calories burned, hours and minutes slept, number of times awakened during sleep, number of highly active minutes in a day, and miles walked) that I’ve written about it twice before this post (here and here). I have no desire to review gadgets as a general rule, but I’ve clearly been seized by the power of this miniature wireless accelerometer.
So much so that in my last piece I found myself questioning calorie monitoring as a practice for weight loss. Although I’ve privately questioned calorie-counting, I never intended to wade into a public debate about it. I love science and writing, but I do not consider myself a science writer, so I generally avoid weighing in (I don’t mind puns—let our metaphorical minds play) on unsettled scientific matters. Whether calorie-counting works is in my estimation one such unsettled matter, but to suggest that calorie counting may not lead to weight loss is to rely on the most outspoken critics of calorie-counting, and those people come with baggage.
I’m talking, of course, mostly about Gary Taubes, whose theory about the cause of the obesity epidemic is not something I have a strong opinion about. (A generous reader introduced me to this intelligent, methodical counter to Taubes.) I am impressed by the smaller claims Taubes makes, the ones we can all agree on (like not all calories—fat, protein, carbohydrates—are created equal). In my own case, watching calories during periods of relative stability has been a curiosity. I have been counting calories with an app on my phone since July and have made little progress. Since I got the Fitbit, I have a more conservative estimate of how many calories I’m burning in a day, which I have used to adjust my calorie intake budget. In the past five weeks, I have burned 10,940 more calories than I have consumed, so I should have lost about three pounds (3500 calories=one pound). The scale says I weigh 0.2 pounds less than five weeks ago. That’s better than the last time I wrote about this, but not much. And I am extremely hungry.
This is all over a range of less than five pounds. The really substantial swings in my weight (15-30 lbs) have always been tied to something much more complex and harder to control: my mood disorder.
I have good anecdotal reason to suspect that my bipolar disorder has a strong metabolic component. Since college, fluctuations in my weight have accompanied every episode, however minor. In 1997, during my first major mixed state episode, I lost thirty pounds inside a couple months (compare to the past five weeks of no progress). That is not normal, and was certainly not prompted by a sudden enthusiasm for fitness. That time, there may have been a slight decrease in appetite (though I never quit eating), which means I don’t know about my rest metabolism in those months, but in the years that followed I would see similar changes in weight with no change in diet or exercise. About that, you just have to trust me.
At the risk of adding another layer of scientific speculation, I want to stress: I am only raising the question here. I wish there were more research on the bipolar metabolism. With more questions than answers, I have no choice but to make guesses based on my own experience, at the peril of drawing unfounded conclusions (falling into those cognitive potholes like confirmation bias and all the other messy human heuristics that science is supposed to correct for) at every step in the process.
In the late 1980s, I saw an image I would never forget.
For some reason I tucked the image away in my memory long before there was a compelling need for me to know about this: PET scans of depressed brains, hypomanic brains, and euthymic (non-symptomatic) or normal brains, and while the depressed brains showed minimal metabolic activity, light bloomed in hypomanic brains where glucose was actively being metabolized. (This imagery has resurfaced some due to neurologist Helen Mayberg’s recent work with depression.)
Now, glucose in the brain is not fructose somewhere else. I don’t pretend to know what mechanisms might be involved, but it sure is hard to have my particular set of experiences to not find the correlation of weight loss with mania as meaningful. (And weight gain with depression—but this is a perfect example of how confused the situation is: many, many people lose weight while depressed. Short-term depression has caused even me to lose weight, but mine was never simple, unipolar depression. There was always at least a mixed, if not hypomanic or manic episode on the heels of short-term depression. Which is often followed by a terrible crash, but that’s another story.)
What this meaningful correlation is—that is the question I am raising. I can’t talk about causation yet, because I’m not even sure we have all the factors on the table. (I haven’t said a word about medication, which in some cases has predictable and somewhat understood effects—there’s no room for that here!)
Let me be clear: despite lack of progress on the weight front, the Fitbit is an excellent motivator. The real attraction of this device for me was monitoring my sleep, but that’s one thing I have little control over. It still feels like I have little control over my weight. However, if it’s 9 p.m. and I’m only 1500 steps away from my daily goal, I can and do pace the house, trying to earn that green “Champ!” badge for the day. It’s nice for my brain’s reward center to see that I’ve earned “Champ” status. And it has to be better to exercise than to not, right?
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