User vmuse asked a pretty important question in /r/theketodiet the other day. I thought it was such a good question to think about that I asked him if it was OK for me to repost it (along with my explanation).

The question (and the context):

I’ve read up on keto, and I know it works but I’m getting told that it’s still a calorie deficit issue. I want more info because: …..

For a matter of 3 months I went on a low fat diet. I was 300 lbs. I ate 1100 calories a day, and was walking a mile a day. I had a high protein, low fat diet (lots of turkey etc, lean breads etc). I was hungry non stop, BUT I stuck with it for 3 months, no cheating. I ended up at 305 lbs. The next summer I was at 310. I went on what I thought was Atkins (I stayed in induction, etc aka I did keto without knowing I was doing keto). Over that three month period I probably ate between 1200 and 1800 calories a day, and walked about the same (just to class and back from my apartment). At the end of that period I was 240 lbs.

One diet where I consumed less calories and probably expended more working out, I gained 5 lbs (and it wasn’t oh hey muscle definition, I looked fatter too). If someone else told me this story I would assume they are lying and cheated on the diet, but I didn’t. The other diet I lost 70 lbs in 3 months, and looked a TON better for the first time in my life. I ended up gaining most of it back after a year of eating junk food non stop since I moved back into dorms, but that’s not the point. How did keto make me lose the weight when I was consuming more calories? My thyroid gland does not work, if that matters at all. I was born with a non working one and have taken synthetic thyroid since I was born. When I was young I was tiny and hyperactive, and then in second grade my father decided drugs were more important than me taking my medicine so I went an entire year without it and tripled in weight. Since then only keto has ever helped me lose weight, nothing else. I played basketball in high school where we ran 3-4 miles a day, lifted weights etc … never could slim down.

I think his experience touches on the fundamental question about CICO (Calories In/Calories Out) and the Insulin Hypothesis. There are also plenty of other explanations one could have for what happened to vmuse, and if you have your own, please add it. I found it worth thinking through what happened and trying to explain it based on what I’ve learned over the past 2 years….

The first thing we should do is break down the diets in a way that we can do side by side comparisons on. So here goes:

Caveats
We’re going to just have to assume that everything vmuse reported is correct. It’s easy to say, “Well, the only valid explanation is that he was underreporting his calories on the first diet, which is why he gained weight or otherwise question the integrity of his statements. I’m going to dispense with that all right now: the point of this isn’t to determine whether or not vmuse reported things correctly or not… instead, it’s to use his experiment as the context for a little thought experiment, and ask the question this way: If we accept everything vmuse reports as true and accurate, how would we explain the results?

The Role of Exercise
Next, we’ll remove the exercise from the equation entirely, since its effect is pretty much negligible from what we know. Besides, even if it were like a magical calorie subtraction tool, we would be looking at about 164 calories a day (back of the napkin estimate for reported body weight and distance walked)…and at this rate, vmuse would have lost about 1 lb in 21 days due to exercise.

BMR And The Role of Caloric Deficit
I don’t know vmuse’s age nor his height, so I’m going to pretend he is a 6ft, 300lb (avg), 25yo male and plug this information into a silly BMR calculator and get a BMR of 2679 calories per day. (Yes, I know how horrid BMR is…but we have to use something.)

According to this, under Diet 1 vmuse theoretically metabolized at least 241,110 calories over the three months. (BMR * 90… also, remember BMR assumes the subject stay in bed all day/do no exercise).

Since vmuse only ate 99000 calories, his body got the remaining 142,000 calories from his fat stores (assuming no muscle loss). If, at the end of the day, it’s the calories stupid…vmuse would have lost 40lbs of fat. Except he didn’t. He gained 5 lbs.

Given this, and given our assumption that all the reporting and BMR information is correct (or a sufficiently close approximation of “correctness” for the purposes of this thought experiment), something else is obviously going on to explain the weight gain.

Perhaps Gary Taubes would say vmuse gained weight because he had poor glucose control/poor insulin control. Protein still raises insulin a significant amount, and Diet 1 appears to be a low fat diet based on protein and carbohydrates. Perhaps if vmuse was not already insulin resistant (unlikely at 300lbs) and could handle the glucose surges without an exaggerated insulin response, he would have lost 40lbs on diet 1. But his experience pretty much suggests a diagnosis (insulin resistance) and explains why he gained 5 lbs (a body stores fat, glucose, ketones….when it’s pumping insulin like mad).

Now let’s look at Diet 2…

For this diet, vmuse is eating low carb, high fat, and moderate protein. This should be correcting/mitigating his insulin resistance (or even just becoming more insulin sensitive outside of any pathology). Let’s run the numbers… His BMR is unchanged at 241,110 calories for 90 days, and he consumed somewhere between 108,000 and 162,000 calories worth of high fat, moderate protein and low carb food during that span. Assuming he stayed in bed all day (BMR), he should have lost between 22 and 38 lbs. But he didn’t. He lost 70 lbs.

Why the discrepancy?

My bad math? Probably.

Water weight lost on LCHF vs low fat? Yeah, there’s some there. Let’s just say 7-18 lbs to account for muscle and liver glycogen + water bound up in inflammation.

The point is that vmuse still lost more than he should have if a calorie is just a calorie.

The Insulin Hypothesis
Maybe Taubes’ insulin hypothesis has something to do with this. Perhaps vmuse had poor insulin control on Diet 1, leading to a situation where he couldn’t readily lose weight. In Diet 2 he had much better insulin control/sensitivity and instead of energy being forced into cells for storage (as it is in an insulin-rich environment), he had all sorts of FFAs floating in and out of his cells for use by his muscles for energy. Simultaneously, his liver was cranking out ketones for other cells to use, and what not. This would explain why he lost weight.

Alas, why did he lose the exact amount he did? This probably pushes the limits even of the thought experiment by at least an order of magnitude…and is not really the point of looking at the plausable theories (not laws) that might explain vmuse’s results on each diet.

(For the record, in my calculations I used the standard 1lb of fat = 3500 calories formula that is as convenient as it is flawed. Barring any errors on my part, you should be able to reproduce all my above calculations easily enough.)

Have an alternative explanation that you’d like to offer? Please add it (or link to it) in the comments!