Despite there being more information on health and fitness today than ever before, I’ve found myself getting confused and frustrated by all the mixed messages so I wanted to clarify and pour in my own wisdom from 15 years in nutrition and women’s health.

After what feels like 100’s of hours of research (I’m a such a health and nutrition geek), I’ve found a few principles that seem to be the “keys” to effective and sustainable weight loss. One of them is the importance of building healthy habits into your life. Another one is having the belief you can actually do it.

And there is the actual Science.  And Science doesn’t lie.

In this brief post we’ll talk about what I feel is the most important scientific principle of them all.

TDEE – The Science Behind Weight Loss

Everyday your body burns a specific number of calories just by existing. This is known as your Basal Metabolic Rate. The BMR is based on your weight, height and age.

When you exercise or simply expend energy through physical activity, you burn additional calories. When you combine your BMR with the calories you burn through physical activity, you get your Total Daily Energy Expenditure.

This is what is known as your maintenance calories.

If you eat this amount of calories you will maintain your weight and you are giving your body enough fuel to maintain all its essential functions.

So How Do I Lose Weight?

You lose weight by having a calorie deficit.

A calorie deficit is eating less than your body needs to maintain itself and thus creating a deficit. Ever had more bills than you had money? You had a financial deficit. A calorie deficit is having less energy than you need to stay the same weight.

Let’s say that based on your age, weight, and height your BMR is 1700 calories and through some physical activity you end up with a TDEE of 2300 calories. To maintain weight you simply eat 2300 calories every day.

To gain weight (and build muscle) you eat more than your TDEE and to lose weight you eat less.

Of course, you can also achieve a deficit through burning more calories through exercise however there is a downside in this theory as there is only so far you can go until the calorie deficit becomes dangerous for your body and its functions, especially your metabolism.

Every effective diet I’ve come across, whether it’s high fat, low fat, high carb, low carb and carb cycling uses a calorie deficit to achieve weight loss.

This is why your cycle includes Low Cal days and Fasting Days which means that you will have a NET DEFICIT throughout your week.  So you will be getting all the benefits of a calorie deficit without any of the negatives i.e. you can still build lean muscle (you cannot build muscle in a long term calorie deficit, only maintain) and you will be boosting your metabolism, not harming it, get it?

How Many Calories Are We Talking?

Technically you can eat nothing all day and achieve weight loss through having a calorie deficit.

Many “miracle diets” claim incredible results through eating specific magical foods or using unique protocols. Unfortunately many diets out there are nothing more than glorified Crash Diets. These diets put you into severe caloric deficit resulting in, yes weight loss (usually short term), but they can also cause health complications and damage to your metabolism.

Also your body cannot build lean muscle when it is in calories deficit and our programme is not about making you skinny but helping you to achieve a lean, strong and curvy body which has strength and is healthy in the long run.

To avoid doing damage and so that you can also build lean muscle and increase strength , the general recommendation is to follow a 7 Day Carb Cycle with certain days of reduced calories or reduction of the types of calories based on your activity.

Note that your body can become conditioned to the same repeated exercise. This can affect your TDEE and hence why we shake up your workouts from Tabata, AMRAP and heavy lifting to avoid plateaus and boredom!

I suggest that you use flexible dieting mixed with Carb Cycling to accomplish the goal of creating a calorie deficit in order to lose weight in a healthy and sustainable way, whilst safeguarding the building of lean muscle and to keep your goddess like curves.

The combination of Flexible dieting and Carb Cycling is non-restrictive and allows you to eat all of your favorite foods as long as they fit within your TDEE and macro goals for that day of your cycle.

You could eat unhealthy foods and still achieve weight loss but weight loss and health are not mutually exclusive. My advice would be to fill the majority of your diet with fresh veggies, fruits, nuts, seeds, and healthy fats and smart proteins. This way you can feel great AND achieve weight loss.

Don’t get bogged down by the latest and greatest research coming out of universities you’ve never heard of. All the conflicting diets and controversial advice from health gurus are enough to give anyone a headache.

Focus on your TDEE as your first step to create a custom programme for yourself, which has proven time and time again, to be the most important tool for weight loss and getting healthier.

Just remember that whatever you decide to eat – the above information is enough for the majority of the population to get started losing weight.

Your Total Daily Energy Expenditure (TDEE) is an essential metric to help you achieve weight loss success.

Use this calculator below to quickly find your TDEE.

Total Daily Energy Expenditure Calculator


What is Katch-McArdle calculator?

The Katch Mardle Formula is a unisex formula that uses body fat percentage and lean body mass to calculate a very precise estimate of your basal metabolic rate. This formula tends to be slightly more accurate than other formulas which are based on total body weight.

Our online calculator lets you choose your own personal activity level. This customizes your daily caloric maintenance level (TDEE).

Simply enter your details into the calculator, and your BMR and TDEE will appear below. You can then choose from the chart below, whether you need to decrease, maintain or increase your calories based on your health and fitness goals.

Total Daily Energy Expenditure


Basal Metabolic Rate (BMR)


Total Daily Energy Expenditure (TDEE)

Basal Metabolic Rate Definition:

Your basal metabolic rate is the total amount of energy (calories) your body requires daily just to maintain normal bodily functions, including digestion, circulation, respiration, temperature regulation, cell construction and every other process in your body. BMR is the total of all the energy you use for basic bodily functions, not including physical activity.

At no point should you go UNDER this amount of calories in a day (perhaps other than the occasional FULL DAY FAST) Do not go under this amount on Low Cal or Fast Days.
Under the TDEE results, add this is the amount you put in as your REG CAL DAY. Do not put in less or reduce this for a 7 day Carb Cycle.

Total Daily Energy Expenditure (TDEE) Definition:

Your total daily energy expenditure (TDEE) is also known as your maintenance level because this is the amount of energy (calories) you require to maintain your body weight. If you eat less than your TDEE, you will lose weight. If you eat equal to your TDEE, you will maintain your weight, and if you eat more than your TDEE, you will gain weight. TDEE is calculated by multiplying your BMR by your activity factor.

Before using the data obtained using this calculator, please consult with doctor.

Simple Body Fat Estimator

What to do with this information?

• Using the figure you have come up with in the TDEE box is your Regular Calorie day amount and your BMR is the absolute lowest you can go even on Low Cal or Fast days to maintain healthy levels.