BMI getting close to "Underweight"

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BMI getting close to "Underweight"

This topic contains 12 replies, has 14 voices, and was last updated by  fasting_me 6 years, 1 month ago.

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  • Does anyone know what to do when this happens?  My BMI is currently 18.8, and “Underweight” is below 18.5.  I have been on the diet for a couple of months.  I am on the diet for healing effects (a myriad of concerns, including auto-immune issues and a diagnosis of LCIS).  Even with my health concerns, I am fairly active (walking/running/yoga) and was already slender when I started the diet.  I’m wondering if the benefits of the diet outweigh the negative of effects of being underweight or if I should increase my caloric intake on fasting days, but keep the hours between eating at a maximum.  Will my weight eventually even out, or will I continue to drop weight?  Thoughts?

    Hi Doris, Are you currently doing the 5:2 version of fasting? If so it might be an idea to reduce the number of fast days to one a week and do a 6:1 plan so you can maintain your weight? Alternatively you could try what you suggest and increase the hours between eating so you eat  within an 8 hour window. Worth still keeping refined carbs to a minimum whilst but maintaining your healthy high fibre calorie intake. Let us know how you get on

    I’m also getting close to “underweight”! I’m doing 5:2 for the health benefits and not for the weightloss, i.e low IGF1, blood pressure, blood sugar, etc. I eat like a horse on the “eat-days” and still lose weight! If I go on 6:1, will I still get the benefits I want?? Help!

    Louise in Sweden

    I’m in the same position as you, Sky pigeon; don’t want to lose any more weight but neither do I want to lose the health benefits of fasting..I’m trying to up my calories on feast days to see how I get of luck!

    Me too, I am close to BMI min but was trying it for the other health benefits. My nurse said I should not lose anymore weight. What to do….?

    Hi. I am a petite lady who is not overweight but I wanted the potential health benefits. I have done 2 weeks of 5:2 and lost weight. So I switched to 6:1 for 3 weeks, eating calorie rich foods on the non-fasting days. Sadly, I am still losing weight and I am now underweight.
    I wish to continue getting the health benefits, so what should I do now to stop the weight loss?

    I think the obvious answer is STOP FASTING NOW!
    If you are underweight or close to it, then you should stop fasting, it is as simple as that.

    The scientific answer is obvious too.
    The benefits of fasting are in fact unproven – for sure we will know more in a few years. But lets assume the benefits (aside from weight loss) are real. For someone who is generally fit and healthy, is a healthy weight and eats properly and exercises regularly, the benefits of regular fasting are going to be very marginal.
    However, the risk of malnutrition caused by fasting while underweight are real, proven and very dangerous to your health.

    If your BMI is under 20 I would suggest you stop fasting, eat healthily and exercise regularly.

    I started fasting when my BMI was 20. It is now 18.5 and I am healthy, but no longer fasting as I don’t want to go below this level. Your BMI really depends on your framesize. I have a small frame and look over weight at 21, but around 18.5 – 19 is perfect.
    It is important you have some reserve in case of illness, especially the older you get, so if I was below 18.5 I definitely wouldn’t be fasting, regardless of body frame size.

    Have to agree with glenbrook here. Sounds very sensible.

    It depends – on gender, age, body frame size, state of health and body composition. The shorthand version of the following is that BMI is useful at a population level but may have less use for individuals and this is particularly true for older women. Some of this is behind the designation of the new moralising and demonising of the Public Health scare that is TOFIs (Thin Outside, Fat Inside).

    A very interesting study by Shah and Braverman introduced new categories of ‘normal weight obese’ etc. where they contrasted people’s BMI with their body fat levels. [QUOTE}BMI characterized 26% of the subjects as obese, while DXA indicated that 64% of them were obese. 39% of the subjects were classified as non-obese by BMI, but were found to be obese by DXA. BMI misclassified 25% men and 48% women. [/QUOTE] Likewise: [QUOTE]BMI significantly underestimates prevalence of obesity when compared to DXA direct measurement of percent body fat…

    This misclassification was seen more commonly in women than in men and occurred more frequently with advancing age in women. A more appropriate cut-point for obesity with BMI is 24 for females and 28 for males…Clinicians should consider using 24 as the BMI cut-point for obesity in women, in order to maximize diagnosis and prevention of obesity-related co-morbidities. Public health policymakers should also consider these more accurate cut-points in designing interventions…Our results document the scope of the problem of false-negative BMIs, emphasize the greater misclassification in women of advancing age, and confirm the improved precision available by gender specific revised cutoffs.[/QUOTE]

    As I’ve mentioned elsewhere, I suspected that I had a disproportionate amount of body fat as I started getting closer to my initial goal weight but was larger/fluffier than I’d anticipated. I had a BodPod assessment and discovered that although BMI <23, my body fat was >40% so I was in the ‘normal weight, morbidly obese’ category.

    Since then, I decided to maintain at 125-127lbs for 6 months before seeing if I could reduce my body fat level without compromising my scant skeletal muscle mass. I had a Dexa scan some time after starting that attempt, and at 117lbs, had a body fat level of just over 30% (oddly enough, still ‘normal weight obese’ but better than ‘normal weight, morbidly obese’ 🙂 ).

    I’m now 108lbs for a BMI of <19 with an estimated body fat that is still ‘overweight’ (I won’t be having another Dexa scan until 2015 so can’t report an exact figure). I’ve reduced my body fat so that I’ve theoretically reduced my risk of developing the metabolic disorders (e.g., CVD and diabetes II) that are typically associated with sarcopenic obesity (a category for which I used to meet the definition but I’m probably now merely sarcopenic).

    So weird. I am really thin, always have been. I don’t know what my BMI is but probably near underweight. However, I have been doing 5/2 diet for a couple of months and so far I have not lost any weight. I have found that no matter how little or how much I eat has any impact on my weight. I do eat a lot on non-fasting days and I eat a lot of fat (the good fats). I really not want to lose any weight but i have found the effects of fasting to be to beneficial to stop.
    BMI is a bit passé I think personally.

    BMI is apparently a poor predictor of one’s actual percentage of body fat – seems as though we ought to spend less time focusing on that number, and maybe more time on our overall sense of health, well-being.
    Fasting has been a part of human life for a long, long time; it’s just recently that we’ve been able to measure and document the various characteristics of health, nutrition. Traditionally, fasting has been looked on as a simple, organic means of improving wellness, physical or spiritual.
    For some people, the idea of voluntarily avoiding food for some period of time just seems insane, scary, irrational. There seems to be an almost visceral reaction of fear when the subject is broached. Each of us has to reflect on our own situation, trust our own judgment.

    I think acknowledge your body composition, natural build and general health.
    If your BP is high have a look at your anxiety levels, are they related more so than weight?
    With autoimmune diet perhaps try eating within helpful dietary parameters but try consuming more of that food.

    If I can help more let me know x

    My BMI, after 4+ years of Fasting, is ‘underweight’. And I’m keeping it there. My doctor thinks I’m tremendously healthy. She’s right. What I do have is a weight below which I will not go. When I get there, I add calories, even if it is a Fast Day. We still Fast 2 days/week.
    What makes the difference is that I have a very small frame. My weight is appropriate to my frame and I am still carrying some fat.
    BMI is a guideline, not a number set in stone. I exercise regularly to maintain and try to gain muscle mass. According to my scale, my Fat % is in the 15-16% range.

    petite lady, what does your doctor say?

    In initial studies on dogs and primates, the underweight dogs were the healthier ones. And lived longer, too.

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