How to lose fat – create an energy deficit

bodycompoToday, I’m writing about ‘how to lose fat – create an energy deficit’. It’s quite simple really, if you burn more calories than you ingest, you’ll lose weight / fat – period.

To do this you first need to find out your Total Daily Energy Expenditure (TDEE), refer to my previous blog “How to work out your Total Daily Energy Expenditure (TDEE)”

Once you’ve worked this out, you’re good to go…

A common approach to reducing body fat is to establish a negative energy balance. Research indicates that if the energy deficit is too great then body fat is more likely to return, possibly to an even greater level.

A priority for an effective weight management programme is to lose body fat, whilst retaining as much lean mass (muscle) as possible thereby minimising the fall in metabolic rate. Many studies on this subject have all concluded that a weight loss of 1 lb per week (ideally from body fat) is recommended.

Create a 500 kcal deficit per day = 3500 kcal in a week = approximately 1 lb of fat

This reduction in body weight may be achieved through several different strategies:

  • diet restriction alone
  • exercise intervention alone
  • exercise and dietary restriction combined – most effective approach*

* The combination of exercise coupled with a modest dietary restriction has been proved from numerous studies to be the most effective method for achieving the desired negative energy balance whilst minimising a fall in metabolic rate.

To work out the number of calories in foods / meals, you could use a number of free android apps. My favourite app is “MyFitnessPal”, which helps you keep track of your eating habits and the amount of calories in each meal.



Reduce calories by a combination of exercise and diet to the sum of 500 a day from your TDEE. Try to be honest with your calorie consumption, use an app like “MyFitnessPal” to track your meals and snacks.


How to work out your Total Daily Energy Expenditure (TDEE)

As a personal trainer, I’m often asked how many calories my clients should be eating every day to lose fat. To do this, we must first work out how many calories an individual requires to maintain their current weight. The Harris Bendict Formula, is the most accurate to date in my opinion.


Harris Benedict Formula

This is a calorie formula using the factors of height, weight, age, and sex to determine basal metabolic rate (BMR). This makes it more accurate than determining calorie needs based on total bodyweight alone. The only variable it does not take into consideration is the amount of lean body mass (muscle). Therefore, it will be very accurate in all but the extremely muscular (it will underestimate caloric needs) and the extremely over fat (it will overestimate caloric needs).

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

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

Note:   1 inch = 2.54 cm

1 kg = 2.2 lbs

1 stone = 14 lbs

For example, Tom is 41 years old, he’s 6’2” tall and weighs 14 stone and 6 lbs. Tom works as a painter and decorator but doesn’t go to the gym (we’ll see why his occupation and exercise regime is relevant soon).

Tom’s BMR = 655 + (13.7 * 91.6kg) + (5 * 188cm) – (6.8 * 41) = 2571

Now that we know Tom’s BMR, we can calculate Total Daily Energy Expenditure (TDEE) by multiplying the BMR by the activity multiplier below:


Activity Multiplier

Sedentary        BMR * 1.2       (little or no exercise, desk job)

Light active     BMR * 1.375   (light exercise/sports 1-3 days/week)

Mod. active     BMR * 1.55     (moderate exercise/sports 3-5 days/week)

Very active      BMR * 1.725   (hard exercise/sports 6-7 days/week)

Extra active     BMR * 1.9       (hard daily exercise/sports physical job)

As Tom works as a painter and decorator but isn’t a gym goer, I’m going to decide he’ll go into the moderate active group (activity factor 1.55).

Tom’s TDEE =  BMR * Activity Multiplier

2571 * 1.55 = 3985 calories/day


Another example, this time using a woman:

Jane is 27 years old, she’s 5’5” tall and weighs 8 stone and 8 lbs. Jane works as a sectary and goes to the gym 3 times a week.

Jane’s BMR = 655 + (9.6 * 54.4kg) + (1.8 * 165 cm) – (4.7 * 27) = 1347

I’m going to decide that Jane’s goes into the light active group (activity factor 1.375)

Jane’s TDEE =  BMR * Activity Multiplier

1347 * 1.375 = 1852 calories/day