How do we lose one pound (1lb) of body fat?
Whats the science, you ask? no!?…. well…. anyway, science to follow.
We will start with an energy deficit.
What is an energy deficit? Essentially an energy deficit is establishing a tip of the scales in terms of the food we put into our body vs energy burned by our body. Calories are the unit of measure for energy.
Simply put: a deficit is eating less calories than our body burns. Energy in vs Energy out.
[Check the Instagram post at the very bottom for more info].
Controlling your energy balance is the king of weight control management and it is the way we lose weight, which is hopefully fat and not muscle. However, it is inevitable to lose a little muscle as the result of an energy deficit (more on this another day).
Moving on to the pound of body fat!
Energy is measured in calories or joules. As both these units are very small they are multiplied by 1’000 and referred to as kilocalories [KCal] or kilojoules [KJ] – this is just like MP/H and KM/H and different countries use different measurements (beats me why we have two measures!?!?)
- 1 Calorie [cal] – 4.2 Joules [J]
- 1 Kilocalorie [kcal] – 4.2 Kilojoules [KJ]
- 1 Kilocalorie [kcal] – 1000 Calories [cal]
- 1 Kilojoules [KJ] – 1000 Joules [J]
- 1g of Fat – 9 Kilocalories [Kcal]
You may be thinking the same as me “1 Kilocalorie is 1000 calories!?” Don’t worry, what we know as ‘calories’ are actually Kilocalories. Hence, that 136 calorie yogurt is actually 136 Kilocalories.
‘Yeh, this is all nice Scott, but how do I lose a pound of Fat?’
To lose a naughty pound of fat we need to eat an estimated 3500 Kcal less than our daily energy requirements each week. This, if mathematically and scientifically correct, requires a 500 calorie deficit each day for one week.
Here are some key stats:
Over the week we require a weekly calorie deficit of about 3,500 Kcal. The simplest way to achieve this is with a calorie deficit of 500 calories per day, multiplied by 7 days a week, equating to 3,500 calories. Hence why I will typically suggest to my fat loss clients a ‘500 calorie’ deficit.
Here’s why it is 3500 Kcal:
- Fat is stored in adipose tissue (AT) – this is the outer fat that we feel and want to shift.
- AT is about 20% water and about 80-87% fat.
- 1lb of AT Fat is therefore 453 grams. 453g x 87% = 394g fat. Remember 1g of Fat is equal to 9 Kcal
- I.e. 394g x 9 Kcal/g = 3,546 Cal
- Thus, to lose 1lb of AT Fat, you need to burn 3,500-3,600 KCal
How do I eat -500 calories a day to lose a pound of fat, where do I begin?
My advice is to jump to TDEE calculator, punch in your data and collect your *Estimated* daily number of calories – this will take some playing with to find your actual number (remember its an estimate). From here we can eat 500 calories less and hopefully see some results!!!! Or, if you want to skip all of the hard work….cue the personal trainer, me! Finding your TDEE number can be quite difficult especially if you already eat way less than that number, and eating less is not an option. Then it may be time to for a personal trainer to step in and help you.
Notable point: If your TDEE number is 2500 and you eat -500 Kcal so, 2000 Kcal a day, then we will lose a pound of fat, but not for ever. If you body only weighs 100 lbs soaking wet then if we were to eat 2000 KCal and aim to lose 1lb of weight every week for 100 weeks we would weigh approx: 0 lbs? This isn’t the case. As we lose weight, that TDEE number changes as does our metabolism – it adapts and for good reason, think survival and energy preservation on little to no food. For this reason, progressive overload with exercise and diet brakes are essential, not to mention good for mental adherence! For more info get in touch with me!
Popular diets and how they work:
i.e. Weight-watchers, Cambridge Diet, Atkins, the Zone etc.
All of the diets that are seen advertised, or made popular by celebrities, follow the principle of making sure we eat less energy than our body puts out on a daily basis. The difference, each one has their own approach, a group setting, ‘restricted foods’, communities and/ or a 1-to-1 personal coach. Each of the different diets set out by these companies have had success in terms of weight loss, they have also had a number of unsuccessful attempts/ people who can’t maintain the restrictions and in extreme cases lawsuits! My position is based on individual success, if it works for you, Brilliant! You have found a system and/or a community with support and it works, that’s the main thing – I just hope you are happy and enjoying, not just the diet but, how it affects you. Neither of them are easy but if you are successful that is just amazing! I would only challenge you to ask yourself if you have created a healthy or an unhealthy relationship with food because of this diet? If unhealthy/malnourished, please get in touch with a professional who can help you achieve complete balance and happiness.
Why a personal trainer can help you.
I can help you find out how many calories you can eat to lose weight, I will help you find an exercise plan you enjoy, I will help you to eat healthier foods, I will allow you to eat pizza and lose weight (yes, really!), I will keep you accountable, I will listen to your needs and adjust a plan that works for you. I will provide you with results and a balance lifestyle. Ultimately, it’s about making your life easier!