The 3500-calorie deficit equals 1 lb fat loss myth

Diet this diet that. We have so many diet experts these days. If one wants to lose weight, where does he or she even start? Did I do the Thanksgiving diet right? How do I diet for Christmas? Wait, is there a covid-19 diet? Who do I go to for advice?
I'm not a calorimeter

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In order to be able to help more in need, we have improvised our weight loss program so that we can help more patients who are currently struggling with losing weight.

Have you ever been told that if you lose 3500 calories from your diet in a week, you will lose a pound a week? So you go home all excited and start cutting 500 calories a day so you can cut about 3500 calories in one week. Perhaps your phone app or even a weight loss expert tells you that at this rate you will lose 1 lb a week, meaning 16 lbs in 16 weeks and you’re ecstatic! First few weeks you’re losing some weight but then you’re somewhat stuck. You swear you are logging everything exactly. What’s going on? Using above concept can lead to many people disappointed and give up prematurely on their hopes of losing weight. They may say “I followed it to its T but didn’t lose like I was supposed to! How come?” Unfortunately the 3500-calorie deficit equaling 1 lb fat loss concept is not true.

This actually comes from a paper in 1958. No kidding. Adipose (fatty) tissue was estimated to be around 87% fat (after they took samples from various parts of body), 1 lb (or 454 grams) of body fat tissue has 87% pure fat. So there is 395 grams of pure fat in 1 lb of fatty tissue and with 1 gram of fat equaling about 9 calories, then 9 times 395 grams gives you a little over 3,500 calories. Now if you take out your graphing calculator Ti-89 and take the slope…I’m just kidding, we’re done with math. Well, almost done.

Why isn’t this concept true? We are not bomb calorimeters in a science lab. First, the amount of energy that’s available from a food can vary depending on whether it’s raw or cooked (e.g. in some plants we can absorb more calories from it if cooked because the cooking helps break down the cell walls), and even on how it’s cooked. Then, the energy extracted from an ingested food varies from one person to another due to factors such as the difference in bacteria in our guts. Presence of some bacteria can further break down the food that our body cannot do on its own, meaning more calories can be absorbed. As you can see every person’s ability to extract the energy- calories- from every food is different due to a variety of factors.

If the formula of 3500 calorie deficit equaling 1 lb of fat loss held true forever and you finished every day with a 500 calorie deficit, that would lead to loss of 1 lb a week and 52 lbs a year, 208 lbs in 4 years. Some would start weighing in the negative lbs by now if this were true.

When one loses weight, their metabolism adapts. As one loses weight their body becomes more fuel-efficient. Think of it this way. As you lose weight, your body transforms from a heavy pick up truck to a compact hybrid car. It becomes better at using fuel, i.e. calories, as it gets smaller in size. If we put a weight vest on you or very heavy ankle weights, you’re going to exert a lot more effort to walk 100 yards then without added weight. This is not just when we are active. For every 1 lb of weight loss, one’s resting metabolic rate- the calories body burns while at rest to allow our body to function including breathing, circulation, digestion- can decrease by about 7 calories a day. So as one loses off extra weight, they no longer have to spend as much effort in doing the same activities, including the activity of resting, as they were before. There’s less of body to maintain. So after one loses significant amount of weight, they’re going to have to exert more effort just to retain their weight as opposed to the effort they spent in the past to keep their weight prior to the weight loss.

Have I confused you enough by telling you how everything is not as simple as it seems? The human body is a complex system. Therefore we cannot simply say in equals out or everything is linearly related in our bodies. So, now you took away my formula and told you my life is a lie, what do I do Dr. Efe? I will reveal the secret to the best and perfect way to lose weight in my upcoming book called… I’m just kidding (sorry, I’m full of jokes today…but hey we all have to keep our spirits up one way or another right? Might as well start the week in a jolly spirit!). The last thing we need is another diet book. I’m sure a few already have come out this month, as there’s at least one new fad diet book a month on a regular basis.

I don’t think calorie counting is a bad tool and often can be a very useful tool. Starting to count calories starts making one aware of what they’re putting in their mouth. It doesn’t tell them how much the exact calorie is, as we just discussed, or yet, worse, it doesn’t tell you that besides the 500 calories with that burger you are also getting a free side of saturated fat that’s going to your arteries to help build up a plaque of cholesterol. However, it can be a good starter of bringing awareness to how small things we eat can be actually very calorie dense and how some food have such low calorie density that you can eat as much as you want while filling up your stomach without gaining too much calories. Wait, that’s a wonderful idea. What if we ate lower calorie dense foods that are full of nutrition? We would fill up easily, lose weight, and still get the nutrients we need. We would not have to worry about counting- after all who wants to count their food for the rest of their life- or worry when our next mini portion meal time is coming up. I will leave you with that for now. We will be discussing more nutrition in the upcoming weeks.

Preventive medicine is very important. A key yet often underemphasized component of it is providing correct, sound advice on nutrition to patients. Nutrition is very important, and as a primary care physician I enjoy discussing it with my patients. It’s not only enjoyment. As my oath starts with a duty of not doing harm, this includes not withholding telling them the very foods they eat may be not healthy for them.

Until next time. Have a great week!



Dr. Efe Sahinoglu

Board Certified Physician in Family Medicine and Obesity Medicine



In order to be able to help more in need, we have improvised our weight loss program so that we can help more patients who are currently struggling with losing weight.

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Dr. Efe Sahinoglu, M.D.

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