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> Excess body weight can put stress on your joints, but doesn't generally have any other negative effects. That seems to contradict the Harvard School of Publi

> Excess body weight can put stress on your joints, but doesn't generally have any other negative effects. That seems to contradict the Harvard School of Public Health's article[0] that says: > The results showed that participants with BMI of 22.5-<25 kg/m2 (considered a healthy weight range) had the lowest mortality risk during the time they were followed. The risk of mortality increased significantly throughout the overweight range: a BMI of 25-<27.5 kg/m2 was associated with a 7% higher risk of mortality; a BMI of 27.5-<30 kg/m2 was associated with a 20% higher risk; a BMI of 30.0-<35.0 kg/m2 was associated with a 45% higher risk; a BMI of 35.0-<40.0 kg/m2 was associated with a 94% higher risk; and a BMI of 40.0-<60.0 kg/m2 was associated with a nearly three-fold risk. Every 5 units higher BMI above 25 kg/m2 was associated with about 31% higher risk of premature death. Participants who were underweight also had a higher mortality risk. These findings don't seem to discriminate on the source of the BMI, only on its existence. [0] https://www.hsph.harvard.edu/news/press-releases/overweight-obesity-mortality-risk/ https://www.hsph.harvard.edu/news/press-releases/overweight-...

csours 4y ago
If they didn't control for the ratio of lean body mass to fat, then it doesn't actually contradict my point. If the findings don't discriminate on the source of the BMI, then you just don't know. It's not evidence. > "They looked at participants’ body mass index (BMI)—an indicator of body fat calculated by dividing a person’s weight in kilograms by their height in meters squared (kg/m2)." BMI is the WORST indicator of body fat precisely because it does not account for muscle mass. BMI is only suitable for population level studies, it is not suitable for individual health decisions. Put another way - if I go to the gym religiously, I could gain a few pounds but also lose a few percent of body fat. What will my medical tests show in general? Will my clothes fit better? Will I be able to climb stairs more easily? BMI shows none of that.
- BoorishBears 4y ago
  > BMI is the WORST indicator of body fat precisely because it does not account for muscle mass. BMI is only suitable for population level studies, it is not suitable for individual health decisions. It works for the people who need it most. Sure you might just be some 5% body-fat tren cycling bodybuilder with an "obese" BMI... but in reality for most people the higher up you go, the more urgent of an indicator it is that someone should lose weight for their health.
- TameAntelope 4y ago
  Then why does my source use it as a measurement? Why wouldn’t they be more specific, if being more specific were very important? I’m very familiar with the “BMI is not good!” argument, but if it’s good enough for Harvard’s School of Public Health, it’s good enough for me.
  - csours 4y ago
    My conjecture is that "Changing Body Composition" is a better goal than "Lose Weight" for individuals who are trying to become healthier. As a long term aim or as a population measure, "Lose Weight" or "Lower BMI" fine; however, as a personal goal "Lose Weight" can be demotivating and flat out counterproductive, especially in the short term. It just doesn't work for many many people. If you had a magic wand and changed all of an obese person's fat mass into muscle mass, that would not produce a healthy person. But that doesn't happen in the real world. Here's what happens in the real world - when you start a workout program you gain a little weight. That small weight gain is not bad, but it can be demotivating if your goal is "lose weight". It can stop people from exercising, which is good for long term health. Weight fluctuations are also confounding to the goal of "Lose Weight". I've often heard that a good goal is to lose 2 pounds a week. I have several problems with that. I can lose up to 4 pounds on a long walk. I can gain up to 5 pounds overnight. Neither of those reflect body fat loss (the walk may represent a few ounces). You may say "That's just water weight!" - Ok. How does my scale know that? Being specific is very important in the personal experience of weight loss ahem change of body composition.
    - TameAntelope 4y ago
      When the choices are, “anonymous person on HN” and “one of the most respected institutions for public health education on the planet”, I’m going to tend towards the latter, thanks.

csours 4y ago

If they didn't control for the ratio of lean body mass to fat, then it doesn't actually contradict my point. If the findings don't discriminate on the source of the BMI, then you just don't know. It's not evidence. > "They looked at participants’ body mass index (BMI)—an indicator of body fat calculated by dividing a person’s weight in kilograms by their height in meters squared (kg/m2)." BMI is the WORST indicator of body fat precisely because it does not account for muscle mass. BMI is only suitable for population level studies, it is not suitable for individual health decisions. Put another way - if I go to the gym religiously, I could gain a few pounds but also lose a few percent of body fat. What will my medical tests show in general? Will my clothes fit better? Will I be able to climb stairs more easily? BMI shows none of that.

BoorishBears 4y ago
> BMI is the WORST indicator of body fat precisely because it does not account for muscle mass. BMI is only suitable for population level studies, it is not suitable for individual health decisions. It works for the people who need it most. Sure you might just be some 5% body-fat tren cycling bodybuilder with an "obese" BMI... but in reality for most people the higher up you go, the more urgent of an indicator it is that someone should lose weight for their health.
TameAntelope 4y ago
Then why does my source use it as a measurement? Why wouldn’t they be more specific, if being more specific were very important? I’m very familiar with the “BMI is not good!” argument, but if it’s good enough for Harvard’s School of Public Health, it’s good enough for me.
- csours 4y ago
  My conjecture is that "Changing Body Composition" is a better goal than "Lose Weight" for individuals who are trying to become healthier. As a long term aim or as a population measure, "Lose Weight" or "Lower BMI" fine; however, as a personal goal "Lose Weight" can be demotivating and flat out counterproductive, especially in the short term. It just doesn't work for many many people. If you had a magic wand and changed all of an obese person's fat mass into muscle mass, that would not produce a healthy person. But that doesn't happen in the real world. Here's what happens in the real world - when you start a workout program you gain a little weight. That small weight gain is not bad, but it can be demotivating if your goal is "lose weight". It can stop people from exercising, which is good for long term health. Weight fluctuations are also confounding to the goal of "Lose Weight". I've often heard that a good goal is to lose 2 pounds a week. I have several problems with that. I can lose up to 4 pounds on a long walk. I can gain up to 5 pounds overnight. Neither of those reflect body fat loss (the walk may represent a few ounces). You may say "That's just water weight!" - Ok. How does my scale know that? Being specific is very important in the personal experience of weight loss ahem change of body composition.
  - TameAntelope 4y ago
    When the choices are, “anonymous person on HN” and “one of the most respected institutions for public health education on the planet”, I’m going to tend towards the latter, thanks.