Doing the Calorie Math
When it comes to weight loss, it all boils down to the math equation that is calories in < calories out. If you’ve been on a quest to lose weight for any length of time, you may already have some understanding of this. But if like me, pre 35 lb weight loss, you don’t really understand the role that calories play in weight loss and maintenance – this page is for you.
At its very foundation, weight loss is about eating fewer calories than you expend. If you choose to eat high quality, nutrient dense foods, it’s a lot easier lose weight because it enables you to feel good on fewer calories which makes it easier to stay on course. If you eat crap, you’ll feel like crap, and sticking with it will be more challenging.
It’s easy to make healthy food taste good with some practice, but this post is simply about understanding the math and science that goes on behind the scenes with what it takes to lose weight.
First, know that it generally understood that one pound of fat contains 3500 calories.
Your Basal Metabolic Rate (or BMR) is the rate at which your body uses energy – in short, how many calories you use in one day to simply be alive. You burn calories sitting there in your chair, sleeping, breathing, chewing, blinking – and those calories are what make up your BMR.
Your Active Metabolic Rate (or AMR) is your BMR + how the calories you burn in your day doing everything else, including exercise. Do you sit at a desk all day or are you on your feet all day? The more active you are, the more calories you burn each day. Throw in some exercise and your daily calorie expenditure goes up even more.
These numbers are important because this is what you need to know about yourself in order to determine how many calories per day you should be eating in order to lose weight.
How Many Calories to Lose a Pound?
A 3500 calorie deficit means 1 pound of fat lost
A surplus of 3500 calories means 1 pound of fat gained
How fast you want to lose a pound throws another variable into the equation as well.
How Much, How Fast
If you want to lose 1 lb a week – you need a deficit of 3500 calories off your AMR in that week – or, an average of 500 calories a day under your AMR over the course the week.
2 lbs a week? You need to aim for a 7,000 calorie deficit – or an average of 1,000 calories per day.
1.5 lbs? A 5250 calorie deficit. (3500 calories x 1.5 lbs … you get the idea.)
Let’s suppose your AMR without exercise is 2000.
Simply put, if you ate 1500 calories every day that week, you should lose one pound by the end of 7 days.
If you exercise on any given day and burn 400 calories, your AMR goes up to 2400. Now you can eat 1900 calories and still maintain your 500 calorie deficit to keep you on course to lose 1 lb a week.
It’s very hard to determine what your exact BMR is, but there are plenty of calculators out there to give you a good guess based on your age, weight, height, sex and activity level. A good estimate is all you need.
In short – eat the number of calories equal to your AMR every day and you’ll maintain your weight. Eat under your AMR and you’ll lose weight. Eat over your AMR and you’ll gain weight.
Armed with these numbers, you now know how many calories you need to eat every day to lose or maintain your weight. To lose weight, all you have to do is you stay under your AMR each day. There are certain health conditions and metabolic disorders that make that last sentence inaccurate – but for most people – it really is as simple as that. (of course we all know thought that simple does not necessarily mean easy.)
But even if you undershot your AMR by only 100 calories per day, that would be 1 lb of fat loss every 35 days. That works out to be more than 12 lbs over the course of a year – just with a 100 calorie deficit every day!
It’s important to recognize that it’s a lot easier than you might realize to go OVER your AMR on any given day – this is one of the reasons why calorie counting can be so powerful. When you begin keeping track of how many calories you eat each day, you begin to see how extra calories make their way into your mouth and how quickly it adds up.
Even once you have all the numbers you need, tying it all together and putting it into practice can be tricky. This is where sites like The Daily Plate (the site I’ve used before and like a lot) come into play and do just about all the number crunching for you.
There are lots of things that can play a role in how you feel while you’re losing weight – the types of foods you eat, the ratio of your macro nutrients (protein, carbs and fat), the quality and source of your food, how much you exercise, sleep – the list is long and it gets complicated quickly.
The number of calories you eat every day add up and are ultimately what make the numbers on the scale go up, down or stay the same. Whether you’re an omnivore, vegetarian, vegan, paleo – if you choose to eat gluten-free, no sugar, low fat, junk food only – you really can eat whatever you want and lose weight, but there is of course a catch. If you spend your calories on junk, you’re going to feel like junk. You’ll then be that much more likely to throw in the towel and give up or delay your progress. Making better food choices will enable you to go further and more likely reach your weight loss goals – and eating better gets easier and more enjoyable the more you do it.
Please remember that I am not a doctor or a nutritionist – I’m just a real person who lost weight counting calories. It worked for me and could very likely work for you too. Understanding the science behind weight loss could get you one step closer to the and the healthy weight you want to reach and ultimately, healthier life you want to live.