Refiguring Deficit

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davidrip1
davidrip1 Posts: 70 Member
in Health and Weight Loss
Let's agree that it takes a 3500 calorie deficit to loose 1 pound of body weight. Let's suppose that a body, because of an excess deficit period, readjusted into a starvation mode with a slowed metabolism. How would the 3500 calculation change? Would it need to be refigured to 4500 or 5500 to shed a pound? Or, would it just be more difficult to achieve that 3500 calorie deficit?

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  • Nony_Mouse
    Nony_Mouse Posts: 5,646 Member
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    Also, if you're talking about excessive deficit, as opposed to prolonged deficit, the degree of adaptive thermogenesis will be larger, and less 'fixable'. This was the phenomenon seen in contestants from 'The Biggest Loser' that was widely reported a few years back. One of the many reasons aggressive deficits are a bad idea.
  • PAV8888
    PAV8888 Posts: 13,596 Member
    edited February 2020
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    The Caloric energy derived from using a lb of stored energy to supplement one's daily needs, when mostly provided by fat, is probably closer to 3500 Cal than anything.

    This won't change. What may change with body composition and size of deficit is how much of that energy comes from fat mass vs non fat mass. For example, when I was obese I probably lost weight at a 9+ to 1 fat to lean mass. When I was in the mid-low overweight range this changed to a much less favourable ratio (below 3:1 in fact) which hastily had me pull back from my then 1.5lb a week deficit. This is based on DEXA scans, so some error, and some reasons that may have existed in addition to body weight change--a shoulder injury for example.

    What you're asking more directly is whether adaptive thermogenesis would have an effect on your perception of how many calories it takes to lose a lb. The answer to that is probably yes, assuming you're just using standard "tables" to calculate your expenditure.

    I started trying to move a bit more (4 months and about 5 to 10lbs) and then deliberately losing weight for about 7 months before joining MFP (40lbs). No other data from that time frame as I wasn't counting Calories and my initial weight was above my then scale's max.

    During my first year on MFP, based on my logging and weight trend, my Fitbit(s) overestimated my caloric expenditure by 0.15% of TDEE or 5 Calories (72.5lb loss). My second year by 3.14% or 98 Calories (11.1lb loss). My third year by 4.77% or 147 Calories (2.7lb loss). My next half year was at 2.66% or 80 Cal (pace of 1lb).

    My logging has been much looser since then so results would not be comparable directly. But I have no reason to assume that the gap has grown.

    So I would say that there was an effect that was felt--for example body temperature wise. But it was not overwhelming enough to derail progress.

    I have no reason to suspect Kevin Hall's experimental designs, and his understanding of math while he is drunk sure as *kittens* surpasses the most brilliant moment of math insight I've ever had, I am fairly sure! But he did do an experiment and came up with a bunch of equations that "predict" the apparent increase in deficit you may be looking at moving forward. You can play with his findings here: https://www.niddk.nih.gov/bwp (use expert mode).

    As to the rest of it... you don't really have to worry much as to how many calories exactly it will take. What most of us need to worry about is to establish the preconditions that will allow us to get there. i.e. to make it so that MOST of the days our decisions regarding eating and moving are pushing us at a reasonable rate for our individual circumstances towards the goal that we want. And if we do that... we will get there!
  • davidrip1
    davidrip1 Posts: 70 Member
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    Great response PAV8888! I've only recorded my latest weight loss attempt since January 1 of this year. I use fitbit and grams for my data. My caloric expenditure was overestimated by .06% during January. And now, from February 1 through 11 it has been overestimated by .67%. Incidentally, i was in calorie deficit and lost relevant weight during December. I was in a VLCD during January with significant cardio. I'm not saying that adaptive thermogenesis is involved but just wanted to open the question. I'll see what happens at months end. I've had 3 February nights when a couple glasses of wine were consumed. Isn't this fun?

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