How far to go below your maintenance calories (safely)?

CopperB73

Hi,
I've been reading through because I'm interested in how much of a calorie undershoot is too much.
Advice from this "faq" post..
http://www.myfitnesspal.com/topics/show/10589-for-those-confused-or-questioning-eating-your-exercise-calo

...seems to boil down to:

Don't allow your calorie intake to drop more than 1,000 calories below what you need for maintenance (i.e. the calories you should eat on a day with no exercise). That may mean "eating your exercise calories" (that is, eating extra to make up for the calories you burned doing exercise, so that the net total is close enough to the maintenance amount ).
The less body fat you have, the more important it is to eat those exercise calories: there's not much fat left in the system to make up the defect, so something else will have to be sacrificed to keep the body running - maybe a lower metabolic rate, or breakdown of muscle.

Does that seem about right? Or did I misunderstand it, or there is more to say now?

ladynocturne

If you net total is close to maintenance, then you will maintain your weight. So I'm certain there is a little confusion here.. unless you want to maintain your weight?

If not, I think what you might have read is not to net below your BMR, which is not maintenance, it's what amount of calories your body needs to live if you were in a coma.

Yes, to maintain as much lean muscle mass as possible while losing weight, it's important to try to net close to your BMR.

So if your BMR is 1500, and you went to the gym and burned 400 calories, you'd need to eat 1500+400=1900 calories because.....

1900-400=1500 net calories.

55in13

A couple of things to add into the mix...

Your fat stores can release 31.4 calories per pound of fat per day. You can take your BF% and weight to determine how much fat you have, multiply that by 31.4 and you will know how large a deficit is possible to support with fat loss. Staying under that number does not guarantee you will lose only fat, but going over it guarantees you will lose LBM also. And remember that as you lose fat this number shrinks.

Look for recent threads on adaptive thermogenesis (AT). If you have a large deficit for a while, your metabolic rate may drop 10% to 15%. It's no meltdown and doesn't cause stalls or explain the myth that a lot of people here believe in; if it happens it is gradual and never turns a deficit into a surplus. It is just something to be aware of.

CopperB73

Thanks - I probably should have been more specific about my terminology! I realise now that what I don't understand is how this corresponds with the calculations I see in MyFitnessPal diary

In my current case (as an example) MFP gives me a goal of 1,830 calories. That presumably factors in the weight-loss goal I set up: I guess that, as I'm losing rather than maintaining, this isn't "maintenance" strictly speaking (sorry if I used that term confusingly!).

But, can you help me work this example?: if my goal as calculated by MFP is 1,830, does that mean that I should bear in mind never to end up with a net calories of less than 830 (because that is 1,000 calories below the goal)?

Or is the "goal" number from MFP diary not the right one to be using for these calculations?

Thanks!

ladynocturne

Thanks - I probably should have been more specific about my terminology! I realise now that what I don't understand is how this corresponds with the calculations I see in MyFitnessPal diary

In my current case (as an example) MFP gives me a goal of 1,830 calories. That presumably factors in the weight-loss goal I set up: I guess that, as I'm losing rather than maintaining, this isn't "maintenance" strictly speaking (sorry if I used that term confusingly!).

But, can you help me work this example?: if my goal as calculated by MFP is 1,830, does that mean that I should bear in mind never to end up with a net calories of less than 830 (because that is 1,000 calories below the goal)?

Or is the "goal" number from MFP diary not the right one to be using for these calculations?

Thanks!

The goal of 1830 calories per day already contains your calorie deficit provided you have it set to lose X amount of weight per week. You're suppose to eat 1830 calories per day with zero exercise to lose weight.

If you exercise you will need to log the exercise and eat 1830+whatever you burn.

Unless you currently have MFP set to lose 0lbs per week, the goal you are given right now is not maintenance, it's for weight loss.

Mokey41

MFP gives you a goal with the deficit already built in. If you chose 2 lbs/week it will have already deducted 1000 calories from what it deemed to be your maintenance level. MFP also expects you to eat back exercise calories to bring you back up to the goal but that can be a tricky area because it's pretty hard to be accurate with those numbers.

A good thing to do is figure out your BMR and make sure you are eating above it. BMR is the number of calories you need to survive in a coma and maintain your weight. Your TDEE will give you your calories that you actually use in a day with activity. You need to be eating between those two numbers to lose weight.

CopperB73

Thanks for this body fat percentage take on things!
Hope it's OK if I work an example (to check I've understood, & hopefully to help others).

As a rough-and-ready way of estimating body fat percentage I looked at these web pages, which have sample pics of men and women at different BF%:
http://www.nerdfitness.com/blog/2012/07/02/body-fat-percentage/
and
http://www.leighpeele.com/body-fat-pictures-and-percentages

So I reckon that I'm at about 23% (+/- quite a bit, given this rough way of estimating, but hey, saves getting some callipers).(Parenthetically, I don't crave looking like Gollum, so down to something around 18% looks like a good goal).

Anyway, I currently weigh 95kg, so if I'm 23% lard that is 21.85kgs; =48lbs
48 x 31.5 = 1507.2 maximum calories I can burn from fat each day

So, I think, that suggests not going ~1,500 calories below my MFP "goal" of 1,830 (and bearing in mind that, as you say, once the fat is gone it's gone & so I'd need regularly to recalculate what a safe deficit would be).

But that's reassuring, as I'm most unlikely to end up with MFP telling me my net calories for the day are 330!

(Do let me know if I've misunderstood, and Thanks!)

CopperB73

Thanks for this -
I note we have a BMR calculator on site: http://www.myfitnesspal.com/tools/bmr-calculator

I think that's coming out at what my MFP "goal" would be if I'd said I wanted to maintain weight.

ladynocturne

Please read some of the other posts, I think you really need to understand that the goal of 1830 calories already contains the deficit, you DO NOT need to eat less than that to lose weight.

Set your weight loss to 0lbs per week to find your maintenance calories. Then change it back to 2lbs per week, you'll see it already has the deficit built in.

55in13

You are still trying to use a constant (1000). That comes from the general rule of thumb that 2 pounds is the most you can lose per week safely. A daily deficit of 1000 gives you a 2 pound per week loss. But obese people can lose more than that while they have a lot of fat and people near healthy weight cannot lose that much without losing some lean mass also. Anyway, you cannot use a constant to figure it out. it varies by person, depending on your metabolic rate and body fat.

Mokey41

Thanks for this -
I note we have a BMR calculator on site: http://www.myfitnesspal.com/tools/bmr-calculator

I think that's coming out at what my MFP "goal" would be if I'd said I wanted to maintain weight.

MFP has not given you your BMR as your maintenance plan. An adult male needs to be eating at least 1800 calories a day minimum.

If you post your stats, age, sex, weight, height we can help you figure out a realistic plan.

Bekahmardis

also, keep in mind that, if you are at 23% body fat, there's no WAY you can be obese....no possible way! overweight? Maybe. Obese? Nope.

Your NET calories need to equal your initial goal calories that are set by MFP. So if MFP says to eat 1850 calories, that's what you need to NET.

CopperB73

Thanks -
Yes I have understood that MFP has factored in the calories I would need to lose the amount of weight I specified. If I ate my goal each day, then I ought to lose weight at the rate I set (+/- measurement errors etc.)

But I'm finding I'm usually undershooting (a bit) so - I could make my weight loss goal more ambitious and then make sure to eat those calories, or keep it as-is and not worry about undershooting, provided I'm mindful not to undershoot by too much.

As a practical upshot, it does sound like the simplest thing to do it to alter the weight loss goal and then make sure to eat those calories...


Sorry if it looked like I wasn't reading (or not understanding): on the contrary, I got rather intrigued by the information everyone was giving me...


Thanks again everyone for your patience in explaining.

Bekahmardis

Don't forget to read through In Place of a Road Map if you are becoming intrigued - you can get totally lost in that forum and end up with enough information to make your head swim.

http://www.myfitnesspal.com/topics/show/974888-in-place-of-a-road-map-2k13

ladynocturne

I think it's really great that you're taking all the time necessary to understand weight loss and that you want to do it the right way.

Eating too little can definitely do more harm then good. I understand wanting to have an ambitious goal, but you will end up losing a lot of lean muscle mass over time and be pretty unhappy with how you look once you do reach your goal weight.

Not to mention that when you lose lean muscle mass it becomes harder to maintain a new weight with normal calories because your maintenance calories become lower than someone of the same weight and height.

So please make sure you're meeting your goal.

Mr_Knight

Your fat stores can release 31.4 calories per pound of fat per day. You can take your BF% and weight to determine how much fat you have, multiply that by 31.4 and you will know how large a deficit is possible to support with fat loss. Staying under that number does not guarantee you will lose only fat, but going over it guarantees you will lose LBM also. And remember that as you lose fat this number shrinks.

Using that math for a hypothetical 250 lb person at 35% BF, we get 250 * .35 * 31.4 = 2700 calories.

So if their TDEE is 3000 calories, they would only need to eat 300 calories a day....?

55in13

Your fat stores can release 31.4 calories per pound of fat per day. You can take your BF% and weight to determine how much fat you have, multiply that by 31.4 and you will know how large a deficit is possible to support with fat loss. Staying under that number does not guarantee you will lose only fat, but going over it guarantees you will lose LBM also. And remember that as you lose fat this number shrinks.

Using that math for a hypothetical 250 lb person at 35% BF, we get 250 * .35 * 31.4 = 2700 calories.

So if their TDEE is 3000 calories, they would only need to eat 300 calories a day....?

This is just the calorie math, ignoring macros completely. Under a doctor's supervision, bypass patients often go below 700. Anyway, to get the energy needed to sustain your hypothetical person, the answer is yes. But the point I mentioned about metabolic rate dropping would almost certainly happen and the person would likely need supplements to get enough nutrients. Whether those can be found in anything with that low a calorie total I do not know. The 1200 number often used as a minimum is another rule of thumb - a well balanced diet at 1200 will generally have enough nutrients for an adult.

Mr_Knight

Gotcha. Makes sense.

When I did 1500-1600 cal/day, I was good until I added fitness as a goal. Then I immediately hit a lack-of-energy wall, despite having plenty of fat reserves to draw on. The low draw-down rate of those reserves would seem to explain that, and why I'm now doing much better on a 2200-2300 cal/day regimen.

I suppose we could design an exercise regimen consistent with ultra low calorie and tapping fat reserves, but I imagine the result would require a very large amount of time because the intensity level would have to be quite low. In fact we should be able to work it out - for the same hypothetical individual, we're looking at a burn rate of ~115 calories/hour. Backing out RMR that leaves very little excess for dedicated exercise. Not sure that would even support slow walking. And we still haven't solved the problem of getting nutrients into the body.

Ugh. I would hate my life if I had to live that way.

55in13

Remember that the glycogen stores act as a buffer between provision of energy (metabolizing consumption or stored fat) and burn. So you can exercise with some intensity while you are eating at a high deficit. I did C25K while eating around 1200 total while I still had over 50 pounds to lose. That's not an amazing amount of exercise; 45 minutes of jog/walking and not even every day. It did wipe me out to do that but I had so many false starts on losing the weight and getting frustrated that I decided I had to bear with it until I made enough headway to make it less likely I would turn back. It worked for me; I returned to a nearer normal level after I lost the first 40 or so, lost the last 15 slower and have been maintaining at goal for about 6 weeks. Not long enough to be sure I will be a long term success, but this is the weight I was at for decades, so I feel pretty optimistic. I am not saying this is for everyone; it most certainly is not. But it is one option that works for some.