On 5’4″ I’d assume, unless you are putting in hours of intense exercise each week, that you would NOT lose weight on 2000 calories a day. If you’re female I’d assume you’d maintain at best and if you’re male I wouldn’t expect much of a loss either – if any.
I’d assume you need about 2,200 calories a day, if you’re exercising vigorously, just to maintain weight. Here’s why…
Let me give you all a hypothetical example.
First, let’s say you’re a student of mine and you are a 5’4″ female, 35 years young weighing 185lbs.
We need to know your resting metabolic rate (RMR). Your RMR are the calories you burn in 24 hours doing nothing – and I mean nothing. Not moving – at all. It varies based on gender, age, height, weight, muscle, metabolic function, disease state etc.
In this case this hypothetical student’s RMR is about 1550 calories a day. Those are the calories needed to essentially lie on your back for 24 hours a day – not moving. It doesn’t even take into account regular life movement like walking to the kitchen, brushing your hair, none of that.
Okay, now that we have the RMR we need to factor in whether you have mostly a sedentary lifestyle or an extremely active lifestyle. For the sake of argument let’s assume minimal activity–pretty sedentary. For that we need to bump up the calorie needs by about 20% above the RMR. This bump up for lifestyle takes into account daily movement for everyday living.
1550 X .20 = 310 calories.
So we add 310 calories (daily general movement) to 1550 (RMR). That equals 1860.
Okay, so our student needs 1860 calories a day to maintain weight with NO exercise. 1860 should create no weight gain and no weight loss when consumed, on average, over a 7-day period.
But our student IS exercising so what’s the value of that? Well, because this is a model student she is doing 300 minutes of VIGOROUS exercise a week (5 hours). Those VIGOROUS exercise minutes have a rough value of 2,400 calories for the week. That is calculated at 8kcal/minute of VIGOROUS exercise. If you’re a man calculate yours at 10kcal/minute of VIGOROUS exercise.
Our hypothetical, female student burned 2400 calories in 7 days with vigorous exercise. To get the caloric value of exercise (CVE) we divide 2400 by 7. Here’s the math
2400 / 7 = 342 calories a day.
Cool, so we can now add the CVE to our maintenance calorie needs (MCN) like this
1860 + 342 = 2202 calories a day
2,202 calories a day is needed to MAINTAIN weight.
Alright, and here is where you get your money’s worth.
Our hypothetical student needs 2,202 calories a day to maintain weight. But she doesn’t want to maintain weight. She wants to lose weight. So she cuts back her calories 10-20%. The SECOND that happens guess what happens to RMR – it slows down. Why? Because the body wants to “help you” conserve energy (fat) just in case you are entering a famine period. After all, we are living 100,000 B.C. right and we MIGHT run out of food at some point right? Oh wait, no we’re not. And there will be NO FAMINE. But the body doesn’t care and it doesn’t understand that. It just knows that when you cut calories ITS JOB IS TO PROTECT YOU FROM STARVING TO DEATH.
So, how much does it slow RMR? Between 10% and 25%. It depends on the person.
The base RMR+everyday living movement was 1860 calories a day.
Let’s assume a worst-case scenario. Our student’s body is hyperprotective of ANY cutting of calories so it slows RMR+daily living by 25%. Here’s the math.
1860 X .25 = 465. We need to subtract 465. 1860 – 465 = 1395
So because we have cut calories to lose weight we are NOW dealing with a daily energy expenditure (DEE) of 1395 calories a day before exercise. And this is because our body naturally slows RMR AND reduces the caloric burn value of ALL MOVEMENT including daily-living movement and exercise. It’s not bad – it just is.
Okay, will we EVER get to the caloric target we need to lose some weight? Yes, we’re close now.
Lets assume the goal is to lose one pound a week. Well for each pound of fat we want to lose we need to create a daily caloric deficit of ~500 calories. That’s because, for rough calculations, we assume it takes a deficit of 3500 calories to lose a pound of fat. 3500 calories divided by seven days in a week? 500 calories a day for ONE pound of fat loss.
At this point we know our DEE (daily energy expenditure), our CVE (caloric value of exercise) and we know our DCD (daily caloric deficit). Now we can do some math. The formula goes like this.
DEE + CVE – DCD = TCD (total calories per day)
1395 + 342 – 500 = 1237 calories per day.
JUST WHEN YOU THOUGHT IT COULDN’T GET ANY WORSE OUR STUDENT CUTS HER CALORIES TO AROUND 1000 PER DAY AND SHE GAINS A POUND ON THE SCALE HER FIRST WEEK!
So, at 1237 calories per day, our hypothetical student should be losing at least one pound of fat per week. But our student didn’t lose a pound. Nope. She gained a pound. And she gained a pound eating 1000 calories a day “verified” by a slick fitness app (take your pick). Whoa – this doesn’t make any sense. It violates all kinds of laws of thermodynamics – laws that apply to us all – that are universal like gravity – that none of us can ever escape, refute or deny. Hmmm, so why would the scale go up?
To gain a pound of REAL fat she would have to be OVEREATING 3500 calories a week since it takes about 3500 extra calories in a week to add one pound of body fat. That’s 500 calories on average per day. I said a bit ago our student needs 2,202 calories a day to MAINTAIN. But she gained a pound. So did she eat 2,702 calories a day on average? I HIGHLY doubt it.
So where did the extra pound on the scale come from?
Reasons the scale may go up:
- Student isn’t really eating 1000 calories a day as logged. This can happen in a variety of ways that have NOTHING to do with integrity. Mismeasurements, forgetting to account for a splurge, eyeballing vs weighing/measuring etc.
- Water-weight fluctuators.
The extra pound on the scale this first week is water weight.
Our hypothetical student did NOT gain weight from eating 1000 clean calories per day averaged 7 days in a row. Nope, no way, no how, didn’t happen – not possible. The laws of thermodynamics make this an impossibility. I can also say for sure our student isn’t broken and her metabolism didn’t stop. A “stopped” metabolism means the student is dead. Since she is alive her metabolism is still running.
Also, consider this too – the new student was eating worse before she started her weight-loss regimen and now, after eating better, eating less and exercising more has GAINED weight. Strictly by the numbers? Makes no sense. But it ALWAYS eventually makes sense if we could know the potentially confounding factors as indicated in reasons 1 and 2 above for why the scale may go up in a one-week evaluation.
- Is it her time of the month?
- Did sodium or carb changes occur?
- Was a new medication introduced?
- A new supplement?
- A new over-the-counter sleep aid?
- Did the student recently fly?
- Has sleep been disturbed?
- Did she introduce a new food she’s allergic too?
- Were alcohol, dairy and grains really kept within the guidelines?
- Is she coming down with a cold or is she sick?
All of these factors and more can, over a one-week period, negatively affect the feedback we get on the scale.
I can’t say for sure WHICH water-weight fluctuator is responsible or if it’s even a water-weight fluctuator. I’d have to live with her 24-7 to get a better handle on that. What I can say, for sure, beyond ALL doubt, is the actual eating of 1000 clean calories per day and exercising 300 minutes a week IS NOT the reason for a weight gain. Since it, 100%, absolutely, is NOT the reason we have to put on our detective hats on and look for calories that are sneaking in or give consideration to a temporary water-weight fluctuator issue that may come to pass (e.g., time of the month).
If this student continues truly eating 1000 clean calories a day and exercising 300 minutes a week the body has NO CHOICE but to lose weight (somewhere between 1-2 pounds a week). In one week? The fruits of the efforts may not be revealed – water-weight issues can easily last a week depending on the cause. But over the course of 2-3 weeks? There WILL be a drop on the scale IF the 1000 calories are truly clean and truly the actual calories being eaten.
Oh, and let me at least mention this. 1000 calories a day is about 20% less than what I proposed. Does this mean the metabolism has stopped? Is eating 1000 calories a day going to kill fat loss or even slow it? No. Is there a point where you can eat too little and slow metabolism further? Yes. For sure. Where is that? Something south of 700 calories a day. But even then metabolism doesn’t stop. It may just slow a bit more. This should NOT be misconstrued and mutilated into me saying that everyone should eat 1000 calories a day. No. You should eat as much as you can to still get the results you want. I’m NOT a fan of undereating. But at 1000 calories a day the metabolism is still firing just fine—slower than it is when weight is stabile (not in weight loss mode) but just fine nonetheless.
So what should the student do?
- See if any water-weight fluctuators are present
- Make sure every morsel is truly being accounted for. Weigh and measure ALL easy-to-overeat foods (foods high in starchy carbs or fats). No eyeballing, no guessing.
- Ask me or another Coach to review the food logs if they are as accurate as you can make them and they are detailed. There are almost always improvements we will notice and suggest that can help get things moving.
- Pursue this worthy endeavor and persist without exception (PWE)2
But wait – I thought weight loss was just “eat less and exercise more.” LOL – what a laugh.