Does a 3,500 calorie deficit really = 1 lb of weight loss?

You've prolly heard the axiom that to lose 1lb of weight you have to be burn 3500 calories more than you eat. But is it really true?


It is a common assumption and while there is some basis to it what it doesn’t’ take into account is something we all have to deal with…


We aren’t robots we’re human beings



Which means while that assumption may work for 1 person it does NOT work for everyone. In fact it won’t apply to most people at least not in the long run.


Let’s look at an example.


I’ll start with a 50-year-old male, with a starting weight of 235 lbs and a height of 5’10”. We’ll call him Kris Kringle


Kris works a desk job, and is only lightly active outside of work


Using one of the many online calculators Kris figures that he needs to eat about 3, 000 calories per day to maintain his current weight.


Using that “tried and true” proven formula then in theory by knocking off 500 calories per day, his intake drops to 2,500 calories daily. And he doesn’t plan on changing his physical activity.


Good for him right? Now, let’s take it a bit further as we’ve mentioned the theory is that a pound is equivalent to 3,500 calories, which means that if we take away those 500 calories from Kris every day, he should lose 1 pound per week (500 x 7 days = 3500 calories).


Assuming Kris stays consistent then he should in theory end up at 183 lbs after one year of eating 500 fewer calories every day.


(According to this math, then, he would weigh 0 lbs within 5 years, which should raise some red flags.)


But we know it doesn’t exactly work this way in real life. Not by a long shot.


At the end of a year, Kris gets on the scale. He’s 205 lbs. He’s lost “only” 30 pounds not the expected 52.


What the hell he says to himself. That’s 22 pounds more than I should be!


Kris starts bitching to his wife , Rebecca who smiles knowingly. She’s hit the 50 year mark too, and has been trying to lose weight since having two kids in her mid-30s.



Tell me about it, she says. "I’ve lost and gained the same 10 pounds over and over, even though I’ve been exercising and eating pretty healthy. I don’t get it."


As as many tend to do they start to think: This didn’t work out at all. We expected more.


Maybe we should try that juice cleanse or one of those “miracle boxed food, & energy fizz programs” after all because clearly our bodies are broken.


Nope my friends, nobody is broken. Don’t hit that juice cleanse or spend hundreds of dollars on one of those fad diet programs your co-worker who magically became a “health coach” is selling just yet.


Instead, Kris and Rebecca could both benefit from a clear understanding of how weight loss actually works.


Then they can set appropriate behavior goals, and have realistic expectations for their progress.


Yes, conventional wisdom states that reducing your intake (or increasing your expenditure) by 500 calories a day should lead to about 1 pound of fat loss per week (500 calories a day x 7 days = 3500 calories a week = 1 pound).


And in my opinion that’s a good STARTING POINT. But it not an absolute.


The fact is that conventional wisdom is wrong because as I said earlier we aren’t robots we’re human beings and as such our metabolism is adaptive.


A lot of factors come into play but sticking with our theme one thing is for sure. Your metabolism is not “fixed” therefore it will change.


As you eat less, your metabolism slows, throwing off common assumptions about calorie balance.


Does this mean the 3500 calories = 1 lb is wrong?