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Weight Loss By Numbers: Getting Your Calories Just Right

calories-and-kjIt’s easy to get a bit bogged down with dieting. Well, that’s an understatement and a half. It seems that to be able to lose weight these days, you’ve got to somehow decode the thousands of mixed messages are coming at you from all different directions, invariably covered in a sprinkling of chia seeds and a dollop of peanut butter. Online, in magazines, on TV – it seems that everyone’s health-crazed and no-one’s got it quite right. Some say don’t count calories, some say pay attention to every last plop of milk in your coffee. You can buy bars, shakes, pills and powders that help you drop a dress size or promise you a ‘bikini body’. We’ve got to somehow fit in five a day around a debatable amount of protein and, of course, it’s all got to be organic, free-range, happy, whole, low-fat, low-GI and clean. And then there’s the question on everybody’s lips: to curb carbs or curb carb-curbing?

I’m not here to write out a miracle diet plan for you that manages to account for every mouthful and milligram of nutritional value, but I can tell you the truth about calories – what they are, what they mean, and how many you need to support a sustainable weight-loss program. Phew.

So – what are calories?

A calorie is a unit of measurement that, in chemistry terms, is the approximate amount of energy needed to raise the temperature of one gram of water by one degree Celsius. Which sounds utterly irrelevant to your weight-loss regime, but in everyday, normal-people lingo, these quantities refer to energy consumption through eating and drinking and energy usage through physical activity. In order to manage your weight you need to strike a balance between the amount of calories you ‘burn’ (through respiration and exercise) and the amount of calories you consume in your food.

What’s all this about calorie guidelines?

The current UK guideline daily calorie amounts are 2,000 calories for women, 2,500 calories for men and 1,800 calories for children aged five to 10. It’s suggested we consume this amount of calories in order to maintain a healthy weight, without factoring in the need for weight loss.

Hmm, I’m trying to lose weight though.

That’s where Supplement Judge is here to help. Or, rather, the Harris-Benedict equation is. The Harris-Benedict equation is the most widely used method of calculating your calorie needs (and thus your calorie needs for weight loss).

BMR = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in years)

Er, slow down – what’s a BMR?

Your basic metabolic rate (BMR) is the amount of energy you expend daily without exercising – that is, it’s the amount of calories you’d burn just by sitting on your bum and watching TV all day long. But in reality, you don’t lie in bed all day long – well, one would hope not, anyway. By getting up, going to work, working out – doing anything that involves moving – you’ll burn more calories than this.

Okay. So how do I figure out how many calories I need to lose weight, then?

Next, you need to identify how much activity you tend to do on a daily basis:

  • Sedentary: minimal movement, lots of TV watching, reading, etc. Activity factor = 1.4
  • Light activity: office work, ~1 hour of moderate exercise/activity during the day. Activity factor = 1.5
  • Moderate activity: light physical/manual labor during the day, plus more active lifestyle. Activity factor = 1.6
  • Very Active: active military, full time athlete, hard physical/manual labor job. Activity factor = 1.9

Next, multiply your ‘activity factor’ by your BMR. I’ll use myself as an example. My BMR is 1432 and my activity level tends to be moderate. So I’d multiply 1432 by 1.6, giving me 2273. This is the amount of calories my body tends to use on a typical day (including work, working out, and so on). To lose weight, however, I’d need to eat less than this.

How much less? 

It’s traditionally stipulated that you need to cut 3500 calories from your diet to lose one pound of weight. Over seven days, this means cutting 500 calories a day to total a typical weight loss of one pound per week. So, for example, if I wanted to lose two pounds per week, I’d cut 1000 calories a day from my realistic calorie expenditure (as suggested by the Harris-Benedict equation) – giving me a daily calorie intake of approximately 1273 calories to play with.

Okay, is there anything else I should know?

Yes! You have to consider a few other aspects of your diet and exercise regime before you take the above information as gospel. For example:

  • Resistance and interval training will burn more calories after you stop exercising compared to traditional aerobic training.
  • High-protein diets burn more calories, as protein takes more effort for your body to digest and metabolize.

So why can’t I go too low? Surely the fewer calories I eat, the quicker the weight will drop off?

Don’t cut your calorie level drastically when trying to lose weight. Your body is a machine, programmed to defend your usual weight, so when calories are cut severely — to fewer than 800 to 1,000 a day — your metabolic rate adjusts to conserve the few calories you do give your body. You won’t lose weight any faster than if you allowed yourself to enjoy 1,200 to 1,500 a day, and if you do, the second you start eating ‘normally’ again, you’ll pack on more weight, more quickly.

I see. So if I’m eating the right amount of calories, I can factor in a cheeky 350cal chocolate bar and still remain on track, then? Score!

 Not exactly. If you’re depleting your calorie intake by 500-1000 calories per day, that gives you less room to meet your nutritional requirements. While you’re cutting the energy in, you still need the nutrients – protein to help you build muscle, vitamins and minerals, fatty acids, fibre, etc. That chocolate bar is just ’empty calories’: it’s got the same energy content as any other calorie but lacks many accompanying nutrients. For the same 350 calories, you could eat a filling, nutritious meal containing lean protein and vegetables which will release energy slower, keeping you fuller for longer.

Damnit. So I can never eat a Mars Bar again?

Well, of course you can! The key to a good diet is eating well most of the time. Sometimes it helps to have a little bit of what you fancy to stop yourself from falling off the wagon completely and binging on all kinds of calorie-laden cravings. One Mars Bar isn’t going to ruin your gains (or losses, depending on how you’re looking at it).

Cool! Thanks for the help, SJ.

You are most welcome, dear reader. Just tryna save the world n’at, it’s no big deal.

Erm…

Well, obesity is a big deal!

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About Amy Longworth

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