Can someone clever explain this? (Calories and maths)

[RoryGlory]

Going by the table below I need -410 calories a day to get to my goal.

If my resting metabolic rate is (I believe) 1800

So if I eat 1200 calories a day I have a deficit of 600.

So 1200 - 600 = 600

So to get to -410 ... I would need to burn a further 1010 calories? Is that right?

You need to be at roughly -2220 calories to get anywhere near the weight loss you want.

3500 calories x 28lbs = 98000 ÷ 44 days = 2227

That means you need to be in a deficit of 2227 calories per day.

Ok let's imagine for a moment that your Fitbit is giving you an accurate picture of what you burn each day doing nothing - 1574. I'm going to round it up to 1600 for ease. (Whether your Fitbit is providing an accurate level or not is another matter.)

Now say you eat 1200 calories a day.

Your daily deficit is 1600 - 1200 = 400

Your weekly deficit is 400 x 7 = 2800

Very broadly speaking you need a deficit of 3500 to lose a pound. So with all other things being equal your deficit of 2800 is about right for losing 0.8lbs per week. If you want to lose faster than that, you need a bigger deficit - in theory.

The problem is that it's not that simple and all other things are not equal. As others have alluded to, there are other things at play - your hormones, your body's response to the changes you're making. @TheHeathenOfSuburbia and others have made lots of interesting points on this.

That calculator you've used is incredibly basic and I wouldn't rely on what it's telling you to do.

Oh I give up.

So to answer your last question the calories you would need to see on your Fitbit would be about 2227 + what you consume say 1200 = 3427

Does it still seem doable every day for 44 days?

You're getting such ridiculous figures because your goal is not achievable. Aim for 1lb a week. Its slow and boring but it works.

To make it easier you can just eat your goal weight maintenance calories (1500) and chuck some exercise in for good measure.

And also, if your fitbit says your average calorie use is 1574 then that's including your exercise, because it uses its own data that you generate. Eg my average daily calorie use is 2700 approx but that already takes into account my exercise, I don't add that on top. It depends where you're finding that figure of 1574 on the app. If it's in your daily stats then you'd need to do an additional 6-7km run every single day on top of what you're currently doing to get the additional 410 calories. Plus Fitbit is not exactly accurate anyway.

I know Fitbit is not accurate but it’s the best I have!

Honestly people just keep throwing figures at me. Its making it too confusing.

Some are saying I need to burn in the 2000s and some in the 3000s.

I’d give it a go if I wasn’t given such differing stats!!

I for one am keen to hear how you got on, OP. So... roll on 20th October?

I was happy to update until I got the drop dead comment.

I’d give it a good go but I still have no idea what my deficit should be!

Each time I think I’ve got it then another poster comes along and says something different

So you're at -630ish but by the end of the day you need to be at -2220ish. If you eat anything else you need to burn that off too

I'm using the Lose it! App.

I put in three meals, all the exercise I do and it tells me all I need to know. It's worked out my daily calorie total on the basis of what I weigh, what I want to weigh and how fast or slow I want to do it. For a week I've burnt off what I've eaten for breakfast and lunch mostly. 2lbs down since I started.

So you'll only give it a go if everyone gives you the same number of calories you need to burn, but you won't give it a go if everyone gives you the same advice?

Seriously, you could lose a significant amount of weight in 6 weeks by following a strict low carb, no alcohol, no sugar diet plan and working your ass off in the gym and at home. Forget about the 'numbers', follow those basic principles and you could lose a fair bit, but it will be hard work and you'll have to be very strict every day. Most weight loss is in the kitchen not the gym, so concentrate on what you put in, not what comes out.

It’s going to be more than a 6-7km Run isn’t it? A PP said a half marathon was about 1300 calories so it’s probably about another 3km or so on top of that.

It's the higher of the two.. I would ignore the 1600 you are burning "anyway" and aim to burn off all the calories you eat, and another 410 more on top of that. So if you are eating 1200, burn off 1610 a day not including the amount your fitbit says you are burning every day.

I think you need to burn 3400 total calories per day, while consuming 1200.

This is because you want to lose 28lb. 1lb is a 3500kcal deficit. So 98000 calories deficit total. So around 2200 calorie DEFICIT per day.

So if you eat 1200 calories, you would need to burn 3400 calories to have a deficit of 2200 (1200 - 3400 = - 2200 = 2200 deficit).

I think the muddle is coming between the calories you need to burn on top of your BMR (1600), the daily calorie deficit you need (amount of calories burned more than calories in (2200)) and the expected total daily calories you would need to put to maintain this deficit assuming you eat 1200 calories (3400).

Does that clarify the various different numbers and where they have come from?

That's really basic though and ignores all other factors at play / how realistic it is to burn that many calories a day unless your job involves running about 16 miles

Rafals sorry yes, that was 6/7km (around 400 cals I think?) on top of any exercise she currently does to give that figure. I ran a 25minute 5km today, completely flat out pace and hilly, and burned just shy of 400 cals (according to fitbit) . There's no way I'd do that every day on top of gym and while eating reduced calories. If nothing else, my poor muscles and joints would very quickly refuse to co-operate!

This thread is twisting my head now, it's bonkers!

Most people are giving you the same answer though, just in different ways.

You need a daily 2210 deficit.
You need to burn 1610 on top of your BMR.
You need to burn 3410 including your BMR.
These are all the same thing using the numbers you've given.

The only advice that is conflicting now and is incorrect is that you can do it by running 6/7k on top of what you're doing. Those sums are wrong and are nowhere near enough to get to the numbers you want.

I did a fairly hardgoing three hour turbo session on Saturday plus a parkrun and another short run. I burned less than 2000 calories. Granted I’m a bit lighter than you, but I don’t think the amount you would need to burn is physically possible unless you start doing back to back Ironman races I’m afraid.

Not sure if anyone's worked this out upthread yet, but here's my analysis!

Currently bmr = 1800 which means over 44 days she burns 79200 calories. If you ate 1800 cals a day, you could maintain your weight doing exactly as you do now.,

You want to reduce your weight to the tune of 98,000 calories worth of fat. So assuming you continue to eat 1800 calories, you'd have to do 2200 (approx) calories of additional exercise every day.

If you reduced your calories to 1300, you would only need to do an additional 1700 cals of exercise every day.

Reduce to 800, you're looking at doing 1200 calories of additional exercise every day. So in theory you could do fast800 and run a half marathon every day, but realistically this is impossible and dangerous.

Your goal is impossible OP, unless you want to give yourself some serious health issues.

Hobby yes, my 6/7km was simply looking at the 410 calories stated in the OP but didn't allow for the fact that the calculation is wrong!

As you were.

(And Reading that back, I'm not saying you were wrong! )

Bloody hell sod the maths just crack on - the only way to lose weight is to move more and eat less!

We're all on the same page now hurray!

So OP, are you going ahead with this?

OP- i am planning on losing about a stone and a half in 40 days. I am walking 300 calories worth a day and alternating between 800 cals and 1200 cals of food a day.

So far (since the bginning of the year ) I have lost a stone- but it was done by serious calorie counting for about 3-4 weeks and then ignoring it for the rest if the time.

Happy to have a thread with you if you wish?