How low is too low? (Calorie intake)

[Nhayes91]

My GF has been cutting and she's down to around 130lbs.. she has been down to 125lb before but was eating around 1000-1200 calories and doing long cardio every day, and she stopped losing weight. I read a lot about metabolic slowdown and metabolic damage from layne norton and decided that she was a victim of this, so she reverse dieted and maintained for a little before cutting again. She's now eating 1600 per day with HIIT 3 days a week and has again stopped losing. Is it safe to keep dropping down to 1400, 1300, 1200 calories to continue weight loss? Or will this just damage the metabolism again. I remember reading somewhere no one should go below 1200 ever

[Ralikar]

HIIT 3 days a week burns very little calories... Do real longer cardio... or other more calorie burning activities.

[Miranda]

safe in that low energy availability (energy in minus exercise out) can affect thyroid after a few days, depending on how lean you are. very lean people experience a larger degree of slowdown quicker than fatter people, and i believe there's considerable individual variety to it. some people's metabolisms simply are more 'resistant' to low calories (or they diet smarter ).

but if the deficit exceeds the slowdown, you will keep on losing fat. scale weight can easily stall due to water retention, and water retention can be aggravated by additional stress from high-intensity exercise - such as intervals -, or large volumes of low-intensity exercise.

the energy availability threshold is around 20-25 cals/kg of LBM, or 10-12 cals/pound. so if your GF was 125lbs at 25%, her threshold would be 1,100-1,200 available calories. that is, she could eat 1,500 and burn 300-400 with exercise and be relatively okay. but it really depends on the individual.

if you insist on dieting on low calories, make sure to refeed every 10-14 days for 24-30 hours or so, and don't diet for longer than 6-8 weeks in one go. then take 2 weeks off, eat at maintenance, then repeat.

[Nhayes91]

Thanks Miranda, forgot to mention she refeeds once a week actually to prevent metabolic slowdown, at maintenance and eats about 100% more carbs on refeed days. And Ralikar, sorry but I beg to differ on the HIIT. Calling longer cardio "real cardio" just seems...off. HIIT has been shown to burn more over time because it keeps the metabolism boosted longer

[coconuttree2009]

safe in that low energy availability (energy in minus exercise out) can affect thyroid after a few days, depending on how lean you are. very lean people experience a larger degree of slowdown quicker than fatter people, and i believe there's considerable individual variety to it. some people's metabolisms simply are more 'resistant' to low calories (or they diet smarter ).

but if the deficit exceeds the slowdown, you will keep on losing fat. scale weight can easily stall due to water retention, and water retention can be aggravated by additional stress from high-intensity exercise - such as intervals -, or large volumes of low-intensity exercise.

the energy availability threshold is around 20-25 cals/kg of LBM, or 10-12 cals/pound. so if your GF was 125lbs at 25%, her threshold would be 1,100-1,200 available calories. that is, she could eat 1,500 and burn 300-400 with exercise and be relatively okay. but it really depends on the individual.

if you insist on dieting on low calories, make sure to refeed every 10-14 days for 24-30 hours or so, and don't diet for longer than 6-8 weeks in one go. then take 2 weeks off, eat at maintenance, then repeat.

Oh, Miranda, good one. I did not know this. Very interesting.

Would like to know how to explain this in physiological terms.
I noticed, that the higher the calories on the cut, the bigger the NEAT is, so I figured that low calorie dieting sucks because just going by my body media I noticed that if I have lower calorie diet (1700 kcals), my daily expanditure is around 2300 and if I have 2000 kcal diet, my daily expandure shoots up to around 2600 by not doing anything extra (consciously). Clearly, more food, more energy, higher NEAT on higher calories and the deficit ends up the same.

[Miranda]

Oh, Miranda, good one. I did not know this. Very interesting. Would like to know how to explain this in physiological terms.

http://www.ncbi.nlm.nih.gov/pubmed/8498602/

Induction of low-T3 syndrome in exercising women occurs at a threshold of energy availability.
Loucks AB, Heath EM.
Source

Department of Biological Sciences, Ohio University, Athens 45701-2979.
Abstract

To investigate the relationship between energy availability (dietary energy intake minus energy expended during exercise) and thyroid metabolism, we studied 27 untrained, regularly menstruating women who performed approximately 30 kcal.kg lean body mass (LBM)-1.day-1 of supervised ergometer exercise at 70% of aerobic capacity for 4 days in the early follicular phase. A clinical dietary product was used to set energy availability in four groups (10.8, 19.0, 25.0, 40.4 kcal.kg LBM-1.day-1). For 9 days beginning 3 days before treatments, blood was sampled once daily at 8 A.M. Initially, thyroxine (T4) and free T4 (fT4), 3,5,3'-triiodothyronine (T3) and free T3 (fT3), and reverse T3 (rT3) were in the normal range for all subjects. Repeated-measures one-way analysis of variance followed by one-sided, two-sample post hoc Fischer's least significant difference tests of changes by treatment day 4 revealed that reductions in T3 (16%, P < 0.00001) and fT3 (9%, P < 0.01) occurred abruptly between 19.0 and 25.0 kcal.kg LBM-1.day-1 and that increases in fT4 (11%, P < 0.05) and rT3 (22%, P < 0.01) occurred abruptly between 10.8 and 19.0 kcal.kg LBM-1.day-1. Changes in T4 could not be distinguished. If energy deficiency suppresses reproductive as well as thyroid function, athletic amenorrhea might be prevented or reversed by increasing energy availability through dietary reform to 25 kcal.kg LBM-1.day-1, without moderating the exercise regimen.

http://jcem.endojournals.org/content/88/1/297.long

Luteinizing Hormone Pulsatility Is Disrupted at a Threshold of Energy Availability in Regularly Menstruating Women

Anne B. Loucks and Jean R. Thuma

Abstract

To investigate the dependence of LH pulsatility on energy availability (dietary energy intake minus exercise energy expenditure), we measured LH pulsatility after manipulating the energy availability of 29 regularly menstruating, habitually sedentary, young women of normal body composition for 5 d in the early follicular phase. Subjects expended 15 kcal/kg of lean body mass (LBM) per day in supervised exercise at 70% of aerobic capacity while consuming a clinical dietary product to set energy availability at 45 and either 10, 20, or 30 kcal/kg LBM·d in two randomized trials separated by at least 2 months. Blood was sampled daily during treatments and at 10-min intervals for the next 24 h. Samples were assayed for LH, FSH, estradiol (E2), glucose, β-hydroxybutyrate, insulin, cortisol, GH, IGF-I, IGF-I binding protein (IGFBP)-1, IGFBP-3, leptin, and T3. LH pulsatility was unaffected by an energy availability of 30 kcal/kg LBM·d (P > 0.3), but below this threshold LH pulse frequency decreased, whereas LH pulse amplitude increased (all P < 0.04). This disruption was more extreme in women with short luteal phases (P < 0.01). These incremental effects most closely resembled the effects of energy availability on plasma glucose, β-hydroxybutyrate, GH, and cortisol and contrasted with the dependencies displayed by the other metabolic hormones (simultaneously P < 0.05). These results demonstrate that LH pulsatility is disrupted only below a threshold of energy availability deep into negative energy balance and suggest priorities for future investigations into the mechanism that mediates the nonlinear dependence of LH pulsatility on energy availability.

so

periods start to go wonky at 25-30 cals/kg (10-12 cals pound). T3 starts to drop at 19-25 cals/kg (8-10 cals/pound). having read various reviews, ~30cals/kg seems to be 'the threshold' for the best of all worlds. (ie you don't get disruptions.)

if you measure in kegs, there's a slight difference between energy availability wrt disruptions in fertility and metabolic rate. but once you convert to pounds, it doesn't matter much (not fully correct but hey). so whenever you look at people with menstrual abnormalities, it's likely metabolic rate could be on its way to become compromised.

also

http://www.ncbi.nlm.nih.gov/pubmed/8498602/

Induction and prevention of low-T3 syndrome in exercising women.
Loucks AB, Callister R.
Source

Department of Biological Sciences, College of Osteopathic Medicine, Ohio University, Athens 45701.
Abstract

To investigate the influence of exercise on thyroid metabolism, 46 healthy young regularly menstruating sedentary women were randomly assigned to a 3 x 2 experimental design of aerobic exercise and energy availability treatments. Energy availability was defined as dietary energy intake minus energy expenditure during exercise. After 4 days of treatments, low energy availability (8 vs. 30 kcal.kg body wt-1.day-1) had reduced 3,5,3'-triiodothyronine (T3) by 15% and free T3 (fT3) by 18% and had increased thyroxine (T4) by 7% and reverse T3 (rT3) by 24% (all P < 0.01), whereas free T4 (fT4) was unchanged (P = 0.08). Exercise quantity (0 vs. 1,300 kcal/day) and intensity (40 vs. 70% of aerobic capacity) did not affect any thyroid hormone (all P > 0.10). That is, low-T3 syndrome was induced by the energy cost of exercise and was prevented in exercising women by increasing dietary energy intake. Selective observation of low-T3 syndrome in amenorrheic and not in regularly menstruating athletes suggests that exercise may compromise the availability of energy for reproductive function in humans. If so, athletic amenorrhea might be prevented or reversed through dietary reform without reducing exercise quantity or intensity.

there's a full link to the LH study for more about info energy availability and fertility in women. unfortunately i haven't been able to access any interdasting T3 stuff, but there are available reviews and studies on females, exercise and energy availability on the net like this one. T3 is only one player in overall lowered metabolic rate, but if T3 is low you can expect lower rates for things like, leptin, insulin and such.

leptin seems to be, at least in part, what causes faster rates of metabolic slowdown in [very] lean people, because leptin is produced by fat cells. so there's less in circulation to start with. (on the other hand, low circulating leptin can induce increased sensitivity to itself, so you don't get the hungry > overfeed effect, but that's slightly off point.)

the problem with self-assessed exercise energy expenditure is, of course, that you yourself have no way to adequately estimate energy expenditure i mean, a 120lb woman who incline walks at moderate puf puf pace or does intervals for 20-30 minutes isn't going to burn a buttload of calories.

metabolic studies have women stay at a facility for days, feed them, and have them exercise in a metabolic chamber. the closest you could get yourself is to measure watts output on an exercise bike (try the elliptical, too; it'll make you cry) and then compute that into calorie expenditure.

accurately tracking calorie intake *cough* is arguably a much bigger problem in all the popular 'metabolic slowdown' queries than being on too-low calories. but for women who go batsht crazy when they diet for 16 weeks to get 'stage lean' or women who chronically expend large amounts of energy via exercise (such as recreational runners) while restricting energy intake, it's likely to be a real issue . . . that you can reverse once you start to eat more food.

I noticed, that the higher the calories on the cut, the bigger the NEAT is, so I figured that low calorie dieting sucks because just going by my body media I noticed that if I have lower calorie diet (1700 kcals), my daily expanditure is around 2300 and if I have 2000 kcal diet, my daily expandure shoots up to around 2600 by not doing anything extra (consciously). Clearly, more food, more energy, higher NEAT on higher calories and the deficit ends up the same.

pretty much. the problem with lowering calories is that it's chicken and egg. your maintenance is 2,500. then you drop calories to 2,000, but your maintenance drops down to 2,200. then you add in 300 calories worth of exercise, but it makes you so tired you expend 400 calories less during the rest of the day.

women are pretty much screwed when it comes to dieting. we are smaller and fatter than than men to start with, so we need less calories to diet down for longer to get lean. and once we drop calories low enough for long enough, the baby factory kicks up a storm

[coconuttree2009]

Miranda, you are a star! Thank you for taking time to explain it so nicely.

[sonti]

Thanks Miranda, nice read. I personally vote "metabolic damage" as the fitness buzzword of 2013, all but forgotten by March 2014.

[coconuttree2009]

I have another questions that has been bugging me since reading the material Miranda was so kind to write up:

Given that ~30cals/kg seems to be 'the threshold', would the same rule apply if someone is extra active and burns 2500+ kcals a day as a 110lbs female - would 'the freshold' be at the same point in comparison to female who burns ~2000 a day?

Logically, the threshold should be higher but the indication is based on weight, not activity levels if I am reading it right?

[oregonchick76]

Eating too low for too long just sucks all the way around. Have her eat at or above maintenance (how tall is she?) for a couple weeks, then approach the diet again with a more sensible intake of around 1700. Exercise is quality over quantity - less cardio, more lifting. She's obviously not going to gain muscle in a deficit, but she can maintain it while cutting down.

I see a lot of people doing body part/body building routines. Newbies should be doing a push/pull split for full body routine that is mostly compounds. Don't know what she is doing now, but Starting Strength or other such routine is a good start.

[Miranda]

Given that ~30cals/kg seems to be 'the threshold', would the same rule apply if someone is extra active and burns 2500+ kcals a day as a 110lbs female - would 'the freshold' be at the same point in comparison to female who burns ~2000 a day?

Logically, the threshold should be higher but the indication is based on weight, not activity levels if I am reading it right?

energy availability is based on calories per LBM, not expenditure pe se. you could have two 110lbs women, with one @ 15% BF (93lbs LBM) and the other @ 25% BF (82lbs LBM). for the first one 'the threshold' would be (30cals x 42kgs) ~1,266 available calories and for the 2nd (30cals x 37kgs) ~1,116 available calories. the difference isn't massive, but it's because the examples are tiny and the margins small.

general eyeball maintenance for both* would be 15 x BW = 1,700 calories. you could eat 1,700 and expend 500 with exercise, so your availability would be 1,200. if you wanted to maintain your weight with that level of exercise, you'd eat 2,200.

when people run into trouble it's because they do an hour of cardio 5-6 days a week on 1,400 calories or so. expenditure reaaalllly depends but say a 110lbs not extremely athletic female might burn 450-500 calories running, say, at 10-11kph for 1hr (incline walking/elliptical sort of thing burns a lot less, especially if you spend only 20-30 mins on them). nothing wrong with exercise, but people would do themselves a favour to eat more to compensate for it.

*it'd be a bit higher for the 15% woman (women who have more lean mass and eat a diet high in protein are likely to 'maintain' on higher calories), so the two don't make a good comparison.

if you compared a lean (15%) recreational runner to an average (25%) sedentary woman, the lean runner would weigh considerably less yet have a higher output than the sedentary one. the runner would likely also eat more calories than the sedentary one, yet have lower energy availability.

[Poseidon93]

HIIT 3 days a week burns very little calories... Do real longer cardio... or other more calorie burning activities.

I thought HIIT burns the most calories, even better than steady state. Wasn't that the point of high intensity?

[Miranda]

I thought HIIT burns the most calories, even better than steady state. Wasn't that the point of high intensity?

you'll burn more calories per minute working at a higher intensity (such as running vs walking). but you can't sustain high intensity for long enough to burn much calories overall. you can go for hours at 130-140BPM, but you can't hold 180-190+ BPM for longer than a few minutes max.

sprints aren't much of a 'high' intensity for the total duration anyway, because you spend much of the time in the recovery interval. that is, even if you managed 15 minutes of HIIT, you'd spend 70% of the time puking your brains out. that doesn't burn much

[singeress]

Can I have some input (no hate please), I've been wondering the same thing.

I've been cutting for 6 months (133 --> 112). When I first started out, a 500 calorie deficit for me was 1280 calories. But now, a 500 calorie deficit for me is 860 calories. Then and now, I have the same sedentary lifestyle (homework/school/tutoring job/sleep) aside from jumproping 3x a week and a couple tennis matches. (Also, include 10 min dumbbell workouts when I can, but not consistently)

I'm basically trying to see if this is normal. I know when I was 121 pounds, my body fat percentage was at 28%; that would mean that my lean mass is 88 pounds. So, minimum is 10 calories per pound of lean mass, then that would calculate to be 880 calories, does it mean it's not too low as long as I don't go lower?

[oregonchick76]

Can I have some input (no hate please), I've been wondering the same thing.

I've been cutting for 6 months (133 --> 112). When I first started out, a 500 calorie deficit for me was 1280 calories. But now, a 500 calorie deficit for me is 860 calories. Then and now, I have the same sedentary lifestyle (homework/school/tutoring job/sleep) aside from jumproping 3x a week and a couple tennis matches. (Also, include 10 min dumbbell workouts when I can, but not consistently)

I'm basically trying to see if this is normal. I know when I was 121 pounds, my body fat percentage was at 28%; that would mean that my lean mass is 88 pounds. So, minimum is 10 calories per pound of lean mass, then that would calculate to be 880 calories, does it mean it's not too low as long as I don't go lower?

No, you need to eat more than that. At your age, you should be able to maintain on a minimum of 1600 calories with no exercise. You need to get into a consistent routine of some sort, but you should not EVER need to drop calories below 1000. You should see steady loss at a much higher intake. You have probably been eating way too long in too great a deficit, haven't eaten proper macros (especially adequate protein and fat), haven't been lifting weights consistently and progressively and have lost a lot of muscle. Need to get the diet dialed back in and get on a solid lifting routine.

[Miranda]

I've been cutting for 6 months (133 --> 112). When I first started out, a 500 calorie deficit for me was 1280 calories. But now, a 500 calorie deficit for me is 860 calories. Then and now, I have the same sedentary lifestyle (homework/school/tutoring job/sleep) aside from jumproping 3x a week and a couple tennis matches. (Also, include 10 min dumbbell workouts when I can, but not consistently)

I'm basically trying to see if this is normal. I know when I was 121 pounds, my body fat percentage was at 28%; that would mean that my lean mass is 88 pounds. So, minimum is 10 calories per pound of lean mass, then that would calculate to be 880 calories, does it mean it's not too low as long as I don't go lower?

i don't know where you got your numbers from, but they're not correct. a 133lbs adult would estimate to maintain at 15 x BW = ~2,000 calories. a 112lbs individual would maintain at ~1,700 calories. either way, a 500 calorie deficit would be ~1,500 and ~1,200 calories, respectively.

but those ^^ numbers are meant for adults, not teenagers. you need more calories than someone 6-7 years older, because you are still growing. and just because something is considered a minimum to not cause disruptions in adults it doesn't mean anyone HAS TO diet at those numbers.

teenagers shouldn't engage in chronic low calorie dieting - or any type rigid 'dieting' for that matter - because the developing endocrine system and HP axis are a lot more plastic and vulnerable to stress during puberty than they are in mature adults. chronic poor nutrition during your teenage years can lead to issues such as stunted growth, menstrual irregularities, and disordered attitude toward food/exercise later in life.

[coconuttree2009]

energy availability is based on calories per LBM, not expenditure pe se. you could have two 110lbs women, with one @ 15% BF (93lbs LBM) and the other @ 25% BF (82lbs LBM). for the first one 'the threshold' would be (30cals x 42kgs) ~1,266 available calories and for the 2nd (30cals x 37kgs) ~1,116 available calories. the difference isn't massive, but it's because the examples are tiny and the margins small.

general eyeball maintenance for both* would be 15 x BW = 1,700 calories. you could eat 1,700 and expend 500 with exercise, so your availability would be 1,200. if you wanted to maintain your weight with that level of exercise, you'd eat 2,200.

when people run into trouble it's because they do an hour of cardio 5-6 days a week on 1,400 calories or so. expenditure reaaalllly depends but say a 110lbs not extremely athletic female might burn 450-500 calories running, say, at 10-11kph for 1hr (incline walking/elliptical sort of thing burns a lot less, especially if you spend only 20-30 mins on them). nothing wrong with exercise, but people would do themselves a favour to eat more to compensate for it.

*it'd be a bit higher for the 15% woman (women who have more lean mass and eat a diet high in protein are likely to 'maintain' on higher calories), so the two don't make a good comparison.

if you compared a lean (15%) recreational runner to an average (25%) sedentary woman, the lean runner would weigh considerably less yet have a higher output than the sedentary one. the runner would likely also eat more calories than the sedentary one, yet have lower energy availability.

Thanks a lot, Miranda, for clearing this up.
I was looking for some correlation between activity levels and calorie availability 'freshold' but should stop.