Stefan asked: For fat burning, what is a reasonable time to burn a certain amount of fat? For example to burn a few kilograms healthily, over what period could this result be expected?

Answer…

Body fat is stored under the skin (subcutaneous), between the muscles (intramuscular) and around the organs (visceral).  These fat stores are the body’s largest energy reserve, a lot like a savings account. 

If we eat more calories than our body burns this savings account builds up, gathering and saving energy for a time when we might need it.  This overflow of calories and build up of fat is called a ‘caloric surplus’…it is all the rage nowadays, everyone is doing it! 

Just 100 excess calories a day will BUILD UP your fat stores 10lbs (4.5kgs) a year. 

To burn off our fat stores we need to reverse this process and burn more than we eat, creating a ‘caloric deficit’… not quite so popular!  The shortage of calories forces our body to burn off our fat stores, just like we might dip into our savings account when we are running low on cash. 

Just 100 calories burned off a day will SHRINK your fat stores by 10lbs (4.5kgs) a year. 

The key point to remember here is that fat burning only occurs when a caloric deficit exists – eating less than you burn, or burning more than you eat.  This means that no matter how hard you train in the gym, if you eat the same number of calories as you burn, your fat weight will remain constant.

Your body might burn 2500 calories through normal daily metabolic activity (resting metabolism, movement, digestion).  You might then head to the gym and burn off 500 calories on the cross trainer.  However, if you have eaten 3000 calories your body’s fat stores will remain constant: 3000 in total burned, 3000 in total eaten… no caloric deficit… no fat burning!

Don’t make the mistake of thinking “I burned 500 calories of fat in the gym today”.  It is only burning off fat if it is 500 calories MORE than you ate that day, otherwise it is just burning off what you have eaten through the day.  This is one of the most common misconceptions about fat burning… people forget that it is about energy balance (calories eaten vs calories burned) rather than just how much you burn in the gym.

Now that we’ve cleared that up, here is the calorie deficit timescale -

A 100 calorie deficit a day = 0.2lbs fat loss a week
A 500 calorie deficit a day = 1.0lbs fat loss a week
A 1000 calorie deficit a day = 2.0lbs fat loss a week.

Calorie deficits greater than 1000 calories a day are very hard to achieve and sustain, so amongst people in the know - personal trainers, nutritionists, exercise physiologists - it is widely accepted that the most fat you can realistically burn a week is 2.0lbs (just under 1kg a week).  Total weight losses might be greater than 2.0lbs a week, but this is usually water and/or muscle tissue loss rather than pure fat loss.

So to lose your few kilograms healthily you are looking at somewhere between 3 to 6 weeks of a sustained 500 to 1000 calorie deficit.  

 

Liam Sartorius is a REPS level 3 personal trainer specialising in resistance training and weight loss.  With over 10,000 hours 1:1 personal training, he has a wealth of experience in body shape and body weight change.

Ask Liam about: Fitness Training, Circuit Training, Muscle Building, Muscle Definition, Exercise for Weight Loss, Nutrition for Weight Loss.

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Tags: calories, fat, weight loss