In its simplest form weight loss (or fat loss, or inch loss) is about consuming less calories than you
use up on a daily or weekly basis. Government guidelines suggest women should eat 2,000 Kcal per
day to stay the same weight and for men 2,500 Kcal, but this is a broad generalisation. How many
calories (Kcal) a person needs a day depends on many things, including their weight, how muscular
they are and their level of physical activity, both in general day to day activities and specific activities
done to help weight loss etc or training for a sport.
So, a better place to start is by calculating your Basal Metabolic Rate (BMR), which is the number of
calories your body needs to carry out the basic things required to stay alive, such as breathing and
keeping all your organs functioning. There are many online calculators available to calculate your
BMR which use your height, weight, gender and age to work this out. Click here to work yours out.
Once you have your BMR, you need to factor in how active you are to work out your calorie
requirement per day over a week. Use the multiples below to convert your BMR to a daily target for
Sedentary – use BMR
Moderately active – x 1.2
Active – x 1.4
Very Active – x 1.6
Extremely Active – x 1.8
Now you know what you should eat and drink to stay the same weight, but you want to lose weight,
so you need to make sure that you eat less than you use. A rule of thumb is that a 500 Kcal deficit
per day should result in the loss of approximately 1lb per week. A small calorie deficit is sustainable
We can also adjust our exercise to burn more calories. Aerobic exercise temporarily boosts our BMR,
up to a maximum of 48 hours after a workout for HIIT workouts, as well as burning calories during
the workout itself. However, strength training alters your body composition and so gives a longer
lasting boost to your BMR, as muscle at rest burns more calories than fat at rest. This is why
generally men have higher BMR than women.
Some gyms have special equipment to analyse your body composition and give an even more
accurate BMR as it is based on individual results of body composition.
So, knowing how much energy your body needs based on your current activity levels, and that if you
reduce your food and drink intake, or increase your activity levels, you can lose weight, can you just
drastically reduce what you eat for faster results? Sadly not!
Your body is very clever; it has evolved over 1,000s of years and is able to keep us alive when food is
scarce by adapting how it uses/stores the energy it receives. Therefore, it is not recommended to
drop your intake too far below your BMR (5-10%). If you want to increase the speed of weight loss,
then you should combine the reduced intake with increased energy expenditure, even simply in the
form of increasing your daily steps. If you add strength training to increase your BMR as well, you
will see further changes in your body shape. However, it is worth noting that when you incorporate
strength training into your exercise routines, you may see your body changing shape and shrinking,
but not see such big changes to your weight. This is because 1lb of muscle takes up a lot less volume
than 1lb of fat.
If you follow the above BMR x activity level and work out a 500Kcal deficit per day and you are not
seeing any reduction in weight, then you should consider other factors, such as are you drinking
enough water, does your diet include a good balance of nutrients, are you stressed, are you sleeping
enough, as these things can influence your ability to lose weight/fat. For women, weight naturally
fluctuates during the monthly cycle, so you need to give it some time to see any loses.
The other things to check are, are you really as active as you said you were, and are you recording
your intake correctly, remembering liquid calories as well as solid calories, and any snacks! Using an
app such as “My Fitness Pal” can help you record your calorie intake and monitor the nutrients in
Finally, as you do lose weight/fat, your BMR changes so you should recalculate your target calories
every month or so, to ensure you are still in a deficit.
If you are really struggling, then it could be worth investing in a couple of 1:1 sessions to go through
this in more detail. Contact me for availability or to discuss this further.