I lose weight after sweets

I watched this video today: 

I understand the content does not need to have any scientific value, nor do my opinions below have it. The text below is a copy of what I posted on Twitter (slightly modified), which are thoughts departing from the video, not about the content (link to the thread here)

At first, I thought it made no sense, since all overweighed people I know who started walking regularly lost weight. I kept watching because I felt I should not make "science" from personal experience. I'm glad I kept watching: the information makes sense.

I have observed that I don't lose weight quickly if I don't eat but gain weight if I do light exercise. I also lose weight if I overdo sweets. Over the years, I've met people who had the same issue. If I understand this video correctly (and this is a hypothesis, not science), someone could have those "different systems" (thinking, storing, defending, etc) balanced out differently or triggered to work at different rates depending, among other things, on the type of food we eat. E.g. a hyperactive kid on sugar may not move more (that's not the only way one may express hyperactivity) but have higher brain activity (again, hypothesis only) and therefore lose weight after eating sugar, especially if higher amounts and/or more frequently.

The same kid (or adult) with a tendency to a hyperactive brain could have that brain relaxed after a mild session of exercise, with their "storing system" taking a leading role. If the differences between the peaks and lows were too wide, it wouldn't "just" alter the levels of hormones that affect our stress, sleep and general feelings, but also something more readily and objectively measurable as the weight we store (or lose) in our body.

Now, let me repeat: this is just a hypothesis. I am not a scientist. My personal experience is not science. The video made sense to me, but that does not mean I am even near the truth. Do NOT share this as "it's been found out that". I'm not aware it has. Keep an inquisitive mind and, although it wasn't meant to be creative writing, maybe read this post as a creative essay. Just to be safe. 

Video comment section

I added the following comment I modified it slightly afterwards, when I noticed I was talking in present but should have described what used to happen): "I lose weight when I eat sweets (if lots or too often), I don't lose weight when I fast (for a short period), I used to put on weight when I did light exercise. I was very sceptical during the first minutes of the video and I don't know whether there is any real science behind its content, but in the end, it all made sense to me and, although it wasn't said in the video, now I understand why my body works the way it does (or used to—much more subtle nowadays). Thanks for making the video." 

I also answered to a comment by another user, matejherman5588, which said: "I did my research. This video is a little bit misleading. Especially that part suggesting you can't lose fat by exercising, because no matter what you do, your calorie expenditure will stay the same (~ 2600 kcal for men). This is a bold statement and it is simply not true as such."

"You can check Caitlin Thurber et al, 2019. They measured energy expenditure among ultramarathon runners over a long period. Their expenditure at the beginning of the run was around 6000 kcal/day. After many weeks it was around 5500 kcal/day. It says two things: 1. The statement above is not true at absolute numbers (otherwise it would be again 2600 kcal, which is nonsense). 2. It seems, there really might be some adaptive processes in your body that lower the energy expenditure after some time to a certain extent."

"However, how much and why this happens is still quite unclear. This video is based mostly on two studies from Pontzer et al 2012 and 2016. The design of this study is quite weak and results are very limited. At the end of the study, they even state "... (we) did not examine the effects of imposing increased physical activity on Westerners ... and increased physical activity has been shown to play an important role in weight loss and weight-maintenance programs" "

"So to wrap it up. Some research suggests that even when you exercise, your body may balance your energy expenditure for some amount*, so it *may happen that even if you are exercising, with the same calorie intake, you won't lose fat."

"So basically, if you start jogging for 30 mins every day or going to the gym twice a week, the rise in energy expenditure is not that significant + it may happen that your body will lower the expenditure somewhere else, so if you don't change your calorie intake, you might not get leaner."

"Btw this problem is usually referred to as an additive vs constrained model. Additive = every exercise adds to your basic level of expenditure. Constrained = when exercising, your basic level of expenditure lowers for a certain amount so the total expenditure stays on the same level. I suppose that the truth lies somewhere in between, but we still need to get more precise data through research."

"For those who are interested in details, I highly recommend reading a perspective from Gonzalez, J. T., Batterham, A. M., Atkinson, G., & Thompson, D. (2023)"

I liked the fact that comment mentions specific studies. I don't have the benefit of that knowledge (my field is a very different one nowadays). I felt compelled to answer and I did: "The problem may also be in who is being measured. Hyperactive people after sugar may burn more calories than those ingested (I don't know any scientific study on that, so just wondering, both from personal experience and observing kids for 20+ years in a school context). They may also lower their "calorie burning" after mild exercise (again, something that used to happen very clearly to me when I was young). If I was being part of the research, they would suspect me of eating extra in secret or vomiting foods to ruin their findings :D"