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Ladies that are losing 2lbs/week, what is your secret?

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  • 3011sophie3011sophie Posts: 20Member Member Posts: 20Member Member
    AnnPT77 wrote: »
    Another factor is that some researchers have advanced the hypothesis that humans' bodies can only metabolize a certain amount of stored fat per day, per pound of fat in one's body. I've seen some estimates - extrapolated from related research as I understand it, not "measured" via reseach - that the number may be something in the 20s to low 30s of calories per pound of bodyfat per day. The weight loss rate maximums one usually sees here can be thought of as rough rules of thumb that give most people a risk-avoiding margin below that (and for many, it's well below that). The idea is that if weight loss is faster than fat metabolization can supply, unnecessarily large amounts of lean tissue will be lost, in addition to fat, and no one wants that, right? I grant that all of this is rather theoretical, even speculative . . . but the stakes are high, so a person might want to hedge their bets.

    Thanks for your reply - do you happen to have a source for the estimates of maximum daily fat loss? It sounds like that might be holding the answer I'm trying to get to!

    I've been doing some reading and it seems like the 1-2lb a week and 1200/1500 calorie minimum go back to the AHA and NIH recommendations respectively, but the AHA doesn't have a source for that specific figure, and the NIH recommendations are based on the fact that most of the studies included in a systematic review used that range of 1200/1500, but again doesn't explain why! The NIH also has an alternative recommendation for calculating caloric deficit for weight loss which is 30% of daily calorie needs, which would put the "average" 2000 calorie woman at 1400. But I don't think I've ever seen 30% restriction recommended on this forum or elsewhere.

    I understand that there are risks associated with very low calorie diets and they should only be attempted under medical supervision, I'm really just curious as to where 1200/1500 and 2lb a week were originally decided as the arbitrary rule of thumb cut-off figures.

    (I'm currently supposed to be writing my thesis and this is definitely an attempt to procrastinate!!)
  • kimny72kimny72 Posts: 14,280Member Member Posts: 14,280Member Member
    3011sophie wrote: »
    Danp wrote: »
    Next thing that needs to be understood is that a human requires a certain amount of calories per day to sustain life. As in not have organs (including heart and brain) begin to deteriorate and shut down. This is different for everyone but the ballpark figures are approx 1200cal/day for females and 1500cal/day for males.
    But where do these ballpark figures come from? Why is it 1200 and not 1100 or 1300? Or the individual's basal metabolic rate? What research has been used to figure out these ballpark figures?
    Danp wrote: »
    Person A is a 350lbs man who is 6' tall. Maintenance for this person would be somewhere in the vicinity of 3200cal per day. So in order for this person to lose at rate of 2lbs per week he would need to eat approx 2200cal per day. This 2200cal per day is still well in excess of the minimum required to sustain life and is sufficient food that this person shouldn't have too much trouble eating enough to not feel constantly hungry, miserable and deprived
    But if men can safely go down to 1500 according to the minimum figures in the previous paragraph, why should this person be losing at 2lb a week and not 3.5lb a week? Is it the size of the deficit that is unsafe, or the minimum caloric intake itself?

    I know that in reality it's a combination of the two - which is why I'm questioning how readily "1200/1500 calories minimum" and "no more than 2lbs a week" are quoted everywhere without consideration of how to calculate what might be safe for each individual, or how these figures were calculated in the first place, or what the specific risks are if you lose faster or eat a lower intake.

    (sustainable is a whole different question - I'm asking more about the safety)

    Certainly part of it is phrasing. It's about playing the percentages. Could a woman eat 1000 calories for some amount of time and still manage to eat enough nutrients, protein, and fat? Yeah, probably. But it would be super difficult and chances are the vast majority wouldn't. So somewhere along the line, someone made the determination that 1200/1500 was a nice minimum cutoff point where a smallish woman/man could get enough of the stuff they need in a well-balanced diet.

    As far as the rate of loss, and I apologize I don't have a source, my understanding is that the recommendation is to lose less than 1% of your body weight per week, and that this is based in some way on the rate at which your body can physically burn fat. If you lose weight faster than your body can burn fat (it doesn't just instantly vaporize it, it's a process), it has to start going after your muscle as well for fuel. I don't think this is a 100% confirmed number, but a generally accepted theory!

    I would assume that MFP caps it's rate at 2 lbs per week because they are trying to keep users without much weight to lose from choosing a rate that is so unrealistic they hurt themselves, while allowing enough room for those who are heavier to still lose at a fast enough pace that they stay motivated.

    It's really more about the balancing act than a rule, they don't want to take the responsibility of forcing people to use this tool in a specific way, but they also don't want the responsibility of people hurting themselves because the tool allows the far extremes. And on the forums, we don't (and shouldn't!) want to take that responsibility either. In the absence of knowing someones medical history, psychological history, and often lots of pertinent details they leave out, erring on the side of caution is just good form IMHO.

    And as @AnnPT77 suggested, it's a lot of our experience, both personal and what we've seen here on the forums for years. We do get posters who are losing super fast, eating super low, everything's awesome, and they tell us it's silly to warn people off losing fast. Then they disappear for a few months. Then they return, shocked that they are struggling with fatigue, appetite, and either a thinner body they still don't like or yo-yo weight gain.

    I think the Biggest Loser study is a good example of why aggressive weight loss has lots of drawbacks. Adaptive thermogenesis (as part of hormone disruption in general), a trickier transition to maintenance, focus on aggressive strategies of weight loss rather than learning how to eat and exercise for maintenance, long term consequences of the stress that fast weight loss puts on the body, these are all things to think about. None of these are carved in stone, but they are all real risks that real life people have experienced.

    ETA: I didn't see your last post before saving this, that's why it might seem like I didn't take it into consideration :smile:
    edited September 16
  • AnnPT77AnnPT77 Posts: 12,716Member Member Posts: 12,716Member Member
    3011sophie wrote: »
    AnnPT77 wrote: »
    Another factor is that some researchers have advanced the hypothesis that humans' bodies can only metabolize a certain amount of stored fat per day, per pound of fat in one's body. I've seen some estimates - extrapolated from related research as I understand it, not "measured" via reseach - that the number may be something in the 20s to low 30s of calories per pound of bodyfat per day. The weight loss rate maximums one usually sees here can be thought of as rough rules of thumb that give most people a risk-avoiding margin below that (and for many, it's well below that). The idea is that if weight loss is faster than fat metabolization can supply, unnecessarily large amounts of lean tissue will be lost, in addition to fat, and no one wants that, right? I grant that all of this is rather theoretical, even speculative . . . but the stakes are high, so a person might want to hedge their bets.

    Thanks for your reply - do you happen to have a source for the estimates of maximum daily fat loss? It sounds like that might be holding the answer I'm trying to get to!

    I've been doing some reading and it seems like the 1-2lb a week and 1200/1500 calorie minimum go back to the AHA and NIH recommendations respectively, but the AHA doesn't have a source for that specific figure, and the NIH recommendations are based on the fact that most of the studies included in a systematic review used that range of 1200/1500, but again doesn't explain why! The NIH also has an alternative recommendation for calculating caloric deficit for weight loss which is 30% of daily calorie needs, which would put the "average" 2000 calorie woman at 1400. But I don't think I've ever seen 30% restriction recommended on this forum or elsewhere.

    I understand that there are risks associated with very low calorie diets and they should only be attempted under medical supervision, I'm really just curious as to where 1200/1500 and 2lb a week were originally decided as the arbitrary rule of thumb cut-off figures.

    (I'm currently supposed to be writing my thesis and this is definitely an attempt to procrastinate!!)


    Unfortunately, no, I don't have a cite. I did a quick search, to see if I could find a scholarly source, but even on Google Scholar I can't think of search terms that will reliably narrow down the results. A non-scholar search returns all kinds of silly nonsense. ;)

    I swear I read a scholarly source for this at some point (I think a journal article rather than an actual research result), but I didn't bookmark it. Apologies!
  • middlehaitchmiddlehaitch Posts: 8,169Member Member Posts: 8,169Member Member
    As well as @danp’s excellent example of calorie requirements for different size and weight people, there is also the amount of body fat one can burn in a day. (Not high fat ingestion like in Keto)

    There is research out there that shows there is a limit in how much body fat the body can burn in a day no matter how fat you are, before the body resorts to fat free mass.

    Nutrition wise, burning body fat as energy, as we do in a deficit, does not provide us with the nutrition we need.

    Unless one is under a doctor’s supervision, bloodwork drawn regularly to check vitamin and mineral levels as well as other health markers, a high rate of loss, 2lbs a week for a woman 5’1, 145lbs (overweight at 27.5 BMI), for example, has a higher chance of nutritional deficits and short and/or long term negative health consequences.

    The 1200 for women and 1500 for men has been shown, through published research, to provide the minimum nutritional needs for someone within average height and bone structure (outliers under 4’8-10, or over 6’6-8 may have different minimums, I don’t know).

    Men have a higher calorie need (1500) than women (1200) even at the same height, as they have a higher muscle mass than women (not an absolute statement, a generalization), muscle burns calories even at rest, body fat doesn’t.

    You could google scholar for the research on the minimum cal intake, fat burn, etc.

    Cheers, h.


    I made mention of the fat burning limit earlier in the thread
    Here is some research. (Sorry just the abstract. If you need further info the full article should be available)

    https://www.ncbi.nlm.nih.gov/m/pubmed/15615615/
    Equals something like 31cals per lbs of body fat per day.

    Lyle McDonald also talks about it, I think in ref to his RFL hand book.

    Cheers, h.
    edited September 16
  • ahoy_m8ahoy_m8 Posts: 1,878Member Member Posts: 1,878Member Member
    https://www.sciencedirect.com/science/article/pii/S0022519304004175?via=ihub
    This describes an analysis that concludes the maximum energy that can be extracted from stored fat is ~31 kcal (+/-3kcal) per pound of stored body fat per day. More stored fat -> more energy available from fat stores -> bigger deficit (without LBM loss)

    If you are that interested, you might also want to look at reviews on this paper. There is disagreement.
    edited September 16
  • AnnPT77AnnPT77 Posts: 12,716Member Member Posts: 12,716Member Member
    Thanks for bailing me out on the cites, @middlehaitch and @ahoy_m8 !
  • DanpDanp Posts: 1,351Member Member Posts: 1,351Member Member
    Zombie thread delivers value! Love it.

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