There are so many factors in fat loss that it can be mind boggling. Anything like stress, lack of sleep, macro levels, carbohydrate manipulating, exercise levels and so on and so on. These are things I write about often. I like to write about the things outside of calories as they honestly have a bigger impact over a lifetime of healthy eating. We need to correct things like our lifestyle habits, social habits, eating habits and exercise habits before we strictly concentrate on calorie intake because if those things aren’t fixed we can’t have a long term solution to fat loss. But today I want to go through the quick math of calories in vs calories out to create fat loss.
The formula to lose 1# of fat is 3500 calories equal 1 pound weight loss. Now this can’t be guaranteed to strictly be fat, there could be some muscle in that as well but we are going to work from the side that it’s just fat for the sake of this.
My goal of this article is to put realistic expectations for how much weight you could lose in a week which then can be extrapolated over weeks, months, years. We are going to use a 150 lbs woman as our example for today’s article. First we need to figure out what her basal metabolic rate (BMR) is. This tells how many calories her body would use if she just laid in bed all day long, never moved. A very simple (not perfect) but quick way to calculate this is to take bodyweight x 100. So her BMR is 1500 for our calculation. Then you need to add in activity levels without exercise, so going to work, chores things like that. Normally we can see up to 500 calories from this on the high side. So just to function during a day this person normally needs to take in 2000 calories.
We know it takes 3500 calories to burn 1 lb of fat. Also, based on heart rate monitoring over many years we know that during 60 minutes of exercise that has any level of intensity we will see at most 400 calories burnt. So we are going to use that for our calculations.
First let’s reduce this person’s calorie intake each day. She can most likely get away with 500 less calories each day. It’s a decent amount down and more than I like to decrease but it’s definitely not unreasonable. In this article, I want to challenge the extremes because people always tell me, but I can do it. So I want to make sure I include you guys as well. So this lady now reduces her calories by 500 each day, so just in calorie reduction she has lost 1lb this week!
This person also worked out 1hr every day with intensity. This probably isn’t overly realistic that they can do it as hard as it takes and still recover properly to not break down muscle instead of fat but we are going to extremes right now. So this person also burnt 400 x 7 which is 2800 calories burnt which is about .7 lbs roughly.
So based on burning 400 calories + eating 500 less calories this person has a 900 caloric deficit each day. If they were to continue to do this over a week they would about 1.7 lbs of fat loss in one week. This is why at Game Changing Performance we say that losing weight at a rate of 1-2#’s per week is the range we believe is sustainable. Heavier people will probably be able to do on the higher side, with lighter people maybe on the lower end of the spectrum. Anything over this won’t be able to sustain for much longer as the above levels of deficits are what we believe to be on the harder end of maintaining.
Could you exercise longer, of course. You probably won’t be able to maintain it at the same intensity but yes you could do it longer and get more calorie burn. However, from training the thousands of people we have trained and knowing the 100’s of thousands of people that struggle with this if not more, when people train too much they end up compensating by overeating. After so long of the deficit their body creates hunger feelings to replace energy. Or it has to start breaking down muscle which will end up in weight loss but you will most likely end up not looking the way you desire in the end.
You could also have a more drastic calorie deficit on the food side as well. This might help you get some initial gains but a few factors will come in to play eventually. One is that you will start to have hormone producing issues which will affecting weight loss for not just the near future but the distant future. Another is you will have the same issue as with exercising too much, you’ll most likely end up with binges weekly that will end up doing the complete opposite of what you intended and you’ll actually put on weight. The third is the idea of starvation mode. There have been many studies on both sides of the fence about starvation mode but in my mind it lumps in with the hormonal issue. After so long, your body will start to change hormonal cues that will slow down your metabolism as it starts to protect homeostasis so you will negatively affect your metabolism.
Now what about the people that lose 10lbs in a week and 20 lbs in the month. We have this happen all the time in challenges, why can they do it? That is an awesome question and yes they actually are losing that much weight but they are NOT losing that much body fat. The first thing they are losing in fecal matter. We can carry up to 10-12 lbs of fecal matter in our intestines. This can cause lots of bloating and intestinal stress. People that eat a lot of processed foods and not a lot of fiber based foods like fruits and vegetables normally have a lot of fecal weight in their body. So when they start to add these in and reduced processed foods, the body cleans that out over a four week period. This thing decreases measurements as well because they stomach isn’t as bloated. Excess water storage is also seen in people who have a less than quality diet. This is from retaining a lot of water do to not drinking enough water. I know that sounds backwards but the more we drink the less we retain as the body doesn’t have to hold on to it for storage. The other thing we see is inflammation decreases. The joints and muscle tissues can hold a lot of inflammation in them. As our diet improves and we exercises our inflammation levels usually decrease because of full range of motion and reduced muscle tension. Positive omega 3’s and healthy nutrients also give our bodies what they need to recovery and we heal much faster. So that initial weight is all lifestyle based weight and has nothing to do with fat loss. So over 4 week these people could lose a legit 8-10 lbs in body fat especially if they are larger but the other 10 lbs is not body fat and is misleading in terms of how much weight can be lost in a given amount of time. The fitness industry really plays on this and really confuses people on what is possible.
That’s where the process of fat loss is so important. It’s not about how much you can lose in a week, it’s about how much you can lose in 3 months, 6 months, a year and so on. So if you have 30lbs to lose, divide that by 2lbs or honestly 1.5 is more realistic and if you are PERFECT that’s how many weeks it should take you to achieve that weigh loss. So if you were super awesome and always exercised 7 days a week with intensity and always ate that calorie deficit it would take you 20 weeks or about 5 months to lose 30lbs. Now this might be discouraging because in your head you were going to lose that in about a month. But I think it should be the opposite, it should be inspiring. Because it probably took you 5 or more years to get to your weight and it only takes 5 months to get rid of it and many of those factors are in your control!!! Heck yea. That is totally awesome. Now it takes hard work and discipline, plus it’s not all a perfect equation but it is achievable. And as I tell all clients, you aren’t that special. Meaning you aren’t the one person in human history that can’t lose weight. You just haven’t been truly disciplined long enough to achieve sustainable results. Most likely you gave it your all for 2 weeks and either were so hungry you just binged or you got discouraged because you wanted faster weight loss. But I’m here to say, it doesn’t work that way, I just showed you the math. The math doesn’t lie, it takes a lot a lot a lot of time. But when you get there it’s worth it, you just have to be willing to stay on the journey.