How does exercise/diet help you lose weight?

So many people seem to be trying to lose weight without really understanding what it is they need to do for that to happen.

People go on diets – How does eating less help?

Sounds like a stupid question doesn’t it?

How about – How does exercise help?

Pretty stupid too... Or is it?

Without knowing how each of these things affects your body in a way that helps you to lose weight, you’re just “doing what everybody else is doing” without understanding why you’re all doing it.

It might have worked for your friend, you may know people who lost weight with a weight management group, but you don’t know what else they did while they were doing that; and how many of those people went on to re-gain that “lost” weight?

Everyone is different, but there is one simple truth that is true for EVERYONE – To lose weight you need to [consistently] burn off more calories than you consume. This means changing your lifestyle, not “going on a diet” which will ultimately end, meaning you start your journey of weight gain all over again.

Without understanding this one simple fact, you go into your diet with no idea of what you are doing or how it will work other than “It worked for________ (fill in the blank)”.

And for those of you who believe that you can do this properly without either exercise or diet (i.e. just do one of them), you’re fighting a losing battle.

What IS a calorie?

Contrary to popular belief a calorie isn’t just a way of seeing how good or bad for you a food is.
Calories ARE NOT bad!

A calorie is simply a measure of energy.

Therefore if we eat 2000 units of energy and only use 1500 units of energy, we store the extra 500 units (yep, as fat).

So, the recommended daily calorie intake for the average female is around 2000 calories (a VERY rough guide that should not be taken as gospel – for a more accurate measure of your daily amount you can use the Harris-Benedict Formula at the bottom of this article).

So, to lose weight you need to be consuming LESS calories than you’re burning. Simple.

But wait!

You can’t simply cut back on your eating and not exercise because your body is programmed to survive – 1000‘s of years ago, people didn’t know when their next meal would be, so we’ve evolved to survive as long as possible without food by holding onto our richest source of energy – fat.

If you cut back on your eating too much, your body will HOLD ON TO FAT, so instead of burning fat stores, it will burn muscle tissue, because muscle tissue needs energy, and your body wants to get rid of anything that’s burning energy.

So while reducing your calorie intake may cause you to lose weight, it will be from muscle tissue NOT fat tissue.

Enter... Exercise

By exercising, you are maintaining, or even building muscle tissue. This is important for a number of reasons.

Firstly, as I mentioned above, muscles need energy to function. Meaning the more you work a muscle, the more energy it needs/burns. So the more muscles you are working, the harder you’re working them, and the more often you work them – the more calories you will burn.

Secondly, the more muscle mass you have to maintain, the more calories you will be burning throughout the day just to maintain that muscle. These calories (if you are burning more than you are eating) will come from fat stores.

So in short, the more muscle you have, the more calories you will burn both during exercise AND throughout the day.

Starting to see why exercise is so important?

Without taking this too much further (you can download my Free report on weight loss from my website), I’ll leave you with a simple calculation that should show why it is important that you use both exercise AND a slight reduction in calories (only slight, or you’ll end up holding on to fat remember) to lose weight/bodyfat.

3500 calories = 0.45kg (just under 1lb) -- so to lose 1lb, you need to burn off 3500 calories MORE than you consume.

Spread this across the week and that means a calorie deficit of 500 calories per day.

Remember if you reduce your calorie intake too much you hold fat, so you need to create this deficit using diet AND exercise.

Reduce your calorie intake by 250kcal per day, AND increase your exercise/activity by 250 calories per day, and you’ve got your 500 calorie deficit. Meaning a steady, healthy weight loss of 1lb per week.

More importantly, by maintaining or building muscle, you won’t gain the weight back again when you “finish” your diet.

If 1lb a week isn’t good enough for you, then you will need to increase the amount of work your muscles are doing (not long runs/bike rides in the gym – work your muscles), but NEVER reduce your calorie intake by more than 500 calories below your recommended amount!

The harder you work, the more you’ll lose.

My book, Fab In 15 Minutes is a collection of 15 minute workouts that burn up to 250 calories each – this is a great way to reach your target quickly and effectively without ever having to set foot in a gym. Visit http://www.fabin15minutes.com/ for these weight loss workouts. If you could consistently lose 1lb a week working just 15 minutes a day would you do it?


To work out your recommended daily calorie intake use the Harris-Benedict formula below:

Men: 66 + (13.7 x weight in kg) + (5 x height in cm) – (6.8 x age)

Example- For a 170cm tall man aged 35 and weighing 90kg:
66 + (13.7 x 90) + (5 x 170) – (6.8 x 35)
= 66 + 1233 + 850 – 238 = 1911 calories


Women:655 + (9.6 x weight in kg) + (1.8 x height in cm) – (4.7 – age)

Example- For a 165cm tall woman aged 35 and weighing 75kg:
655 + (9.6 x 75) + (1.8 x 165) – (4.7 x 35)
= 655 + 720 + 297 – 164.5 = 1507 calories


Once you have this number (your BMR), multiply it by the following depending on your activity levels, to get your daily calorie guideline.

Sedentary BMR x 1.2 little or no exercise, desk job
Lightly Active BMR x 1.375 light exercise/sports 1-3 days per week
Mod. Active BMR x 1.55 moderate exercise/sports 3-5 days per week
Very Active BMR x 1.725 hard exercise/sports 6-7 days per week
Extra Active BMR x 1.9 hard daily exercise/sports AND physical job

So if we take the female example above with a lightly active lifestyle, your daily calorie guideline would be 1507 x 1.375 = 2072 calories per day


Please note, if you are “over-weight”, this calculation will slightly overestimate your caloric needs.


Now you (hopefully) have more of an idea of what it is you’re doing, check out the FREE weight loss report at http://www.markonefitness.co.uk/, and the workout book at http://www.fabin15minutes.com/.