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How Fast Can You Lose Fat?

It's natural to want results as fast as possible. For most people, this means crash diets that bring immediate change to the scale. There is a problem though: your body will not burn all of its fat at once. In fact, your body is going to try to hold on to it. Why? Fat is your body’s savings account.

You see, your body was designed to do amazing things - and that includes storing fat. Until recently, getting calorically-dense food was not as easy as walking to your fridge or pantry and pulling out whatever your heart or tummy desired. In fact, there was even a chance that you could go without food for so long that you would die. To help keep you alive, your body stores fat. In times of scarcity, your body will tap into those fat stores and use it for energy.

While eager-dieters want weight loss yesterday, there are some major negatives to rapid weight loss.

First, it’s important to understand that there is an upper limit on fat loss. Pushing past this limit will cause muscle loss. This creates a skinny fat physique - not fat, or muscular, but also not what you really desire.

Most you can lose per week?

Dr. Alpert looked at several fat loss studies to find what is the sweet spot for fat loss per week. His findings show the human body can burn about 31kcal/lb of body fat /day (69kcal/kg). Anything beyond this and you risk using muscle for energy. While the numbers aren’t a hard rule, they give a good guideline about setting expectation for fat loss.

Meet Gary. Gary weighs 180lbs and was 15% body fat.

This means that Gary has 27lbs of fat (180x.15=27)

Now, multiply Gary’s lbs of body fat by Dr. Alperts 31kcal to see how many calories Gary could burn a day. 27x31= 837 calories. This number gives you your maximum calorie deficit for the day.

Finally, take your deficit, multiply by 7 and divide by 3500. 837x7=5859 is the total deficit you’ll create during a week. 3500 is approximately the amount of calories in a pound of fat. When divide our number by 3500, it shows us the theoretical upper limit of fat loss per week.

In Gary’s case, 5859/3500= 1.67.

Based on these calculations, if Gary doesn’t want to lose muscle (and he doesn't), he should aim to lose around 1.5-2lbs of fat per week, maximum. That means that at the most, he should be looking to lose 8lbs of fat per month.

That’s it.

For most people, a measly, lousy, 1.5lbs down on the scale over the course of a week would feel like a plateau, instead of a tremendous success. After all, that other workout program is promising 10lbs in a week, not a month. This is very short-term thinking.

Let’s get real conservative and say that over the next year you lose an average of 0.5lbs of fat each week. While that sounds lame and slow, that equals 26lbs!

Also, realize that this is the maximum amount of fat you can lose in a week before tapping into muscle. This requires a fairly aggressive approach to dieting that may still result in some muscle loss.

Determining your body fat at home isn’t the easiest. The best way that I’ve found to get you close is to use this calculator.

Initial Weight Loss

When you begin to make healthy lifestyle changes, you may notice that you lose far more than this. This can be a very exciting time, but sometimes you can mistake this for the norm.

This initial whoosh of weight loss will be mostly water weight. It’s important to know this so you can remain realistic about your progress. You may lose 5, 6, even 10 lbs during your first week or two - great! But don’t expect that to be the norm.

How much do you need to lose?

Having realistic goals is important. How much weight do you need to lose? Lots of people overestimate how much weight they need to lose for a higher quality of life.

A woman who weighs 150lbs may want to lose 20lbs and get to 130, but her quality of life would be just as good at 140, or even 145lbs. All the quality of life with a fraction of the pressure.

Meet Leanne. Leanne is 50 years old and has been on a diet roller coaster for the better part of her adult life. She has found herself in an endless cycle of restrict calories-lose weight, binge-gain it all back. She has convinced herself that if she could get to 125lbs she would be happy with herself.

Leanne has some good options:

1) She could pursue 125 and realize that losing 25lbs over a year is only around .5lbs of fat a week. Realizing this she could take a moderate approach, focusing on eating slowly and mindfully to 80% full and eating lots of vegetables, fruit and lean protein.

2) Leanne could realize that at the age of 50, she doesn’t need to weigh as much as she did in high school. When she looks at her real life there is no reason she needs to be a size 2 again. Instead of beating herself up about her weight, she could focus more on healthy habits like eating a little less while improving the quality of her food. She might also focus on 2-3 resistance training workings per week. Instead of focusing so much on the outcome of losing weight, she should focus more on consistency with healthy behaviors.

Leanne may not lose any weight, but if she can drop her body fat from 35% to 25%, she will look and feel drastically different.

If you’re fat loss the right way, you’ll be including some form of resistance training program in your efforts. This means that while you’re losing fat (scale down), you’ll be gaining muscle (scale up). This may lead to weeks where the scale remains the same or… goes up! Therefore the scale is only one metric to use. A better way to track fat loss is to take regular waist measurements, or not at all. Nothing says that you need to measure progress. If you are content eating healthier foods more often than not and doing a few bouts of resistance training throughout the week, that is great.

Finally, what you’ll find is that this theoretical number will probably show up as an average weight loss.

If Gary lost his maximum of 8lbs in a month, it doesn’t mean he lost 2lbs each week. He may have lost 6lbs in his first week, gained 2 back the next week, lost 3lbs in week three and then lost 1 more lb the following week. (-6+2-3-1=-8lbs). This is a small sample size, but you get the picture.

Have realistic expectations for weight loss. While many programs promise wild amounts of weight loss in a few weeks (or days!), it’s simply not healthy or realistic. Weight loss that involves losing muscle is not good.

Taking a slower approach will help make things more enjoyable for you and will lower your chances of a big rebound and gaining all the weight back.

At the end of the day, whether you are a Gary, Leanne or somewhere in between, steward your body. In stewarding your body, you may find that you may want to lose weight but don't need to. If you think losing weight would help you to be strong for your tasks, don't view it as a finish line to get to, but rather a journey to be enjoyed. Take it slow. Enjoy the process.

This article was originally posted at



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