Articles » Lifestyle » General Health » Doctor: Top 5 Reasons You Can’t Lose Weight

Doctor: Top 5 Reasons You Can’t Lose Weight

By Charlie Seltzer, MD / February 20, 2016

Weight loss is the holy grail of most diet and exercise programs. You could also spend a lifetime counting the number of supplements out there which purport to help shed pounds. Still, very few people are successful over the long run in achieving and maintaining a healthy weight. In this article, I will discuss 5 reasons why people cannot lose weight.

It is important to understand that weight loss can be different from fat loss. Ideally, all weight that is lost on a “weight loss plan” is fat, but many fad diets use carbohydrate restriction to force a dramatic water weight loss (with a very real risk of lean tissue loss as well), which, while making the scale move impressively, does little to change the way you look or how your clothes fit.

Five pounds of fat loss will change your appearance much more substantially then five or ten pounds of water loss. Similarly, especially when someone first starts exercising, he or she will build muscle while losing fat, so in the beginning of a training program, other measurements (body fat, waist circumference) are much better indicators of progress than the scale. However, building lean tissue is a much slower process than losing fat, so if your goal is fat loss, the scale can be a very useful measurement, especially if you are not new to weight training. If the scale is not moving and your clothes are not fitting better, it is worthwhile to look at the following.

Why You Can’t Lose Weight #1: Excess Calorie Intake

In order to lose weight, you must eat fewer calories than you burn. Dietary recall can be very inaccurate. In one study, men and women underestimated their calories by 11% and 13% respectively.1 Additionally, many people under estimate portion sizes and have trouble figuring out how many calories are in foods they did not make. And while online tracking applications have made it easier than ever before to log food intake, no existing program is perfect. For example, I looked up a particular protein bar on Myfitnesspal and found 3 entries that understated the calories by as much as 40%. If you are not careful when logging, you may end up gaining weight even with the best intentions.

Why You Can’t Lose Weight #2: Metabolic Issue

Underactive thyroid, for example, may be much more common than previously thought. There is great disagreement among medical professionals as to the best way to diagnose and treat hypothyroidism.2 Hormonal imbalances, especially in women, can predispose to weight gain. For example, extra estrogen in relation to progesterone can contribute to weight gain. High levels of the stress hormone cortisol can cause weight gain indirectly by increasing appetite.

Recommendation: Have your hormone levels checked if you think this may be an issue, but understand that weight loss requires eating fewer calories than you burn regardless of your hormonal status.3

Why You Can’t Lose Weight #3: Medications

There are a number of medications that can cause weight gain. Antihistamines like Benadryl can cause significant weight gain (The American Society of Bariatric Physicians estimated up to 10 pounds per year), as can antidepressants and certain blood pressure medications, among others.

Recommendation: If you are having trouble losing weight, go over your medication list with your doctor and look for alternative medication if something you’re on is associated with weight gain.

Why You Can’t Lose Weight #4: Relying Only On Exercise

Our bodies are very efficient, and simple math breaks down when it comes to calories burned versus consumed. There are metabolic and behavioral adaptations that vary significantly from person to person and are not accounted for using simple equations. For example, John goes out and walks a mile. He estimates a burn of 100 calories, so he treats himself to a 100-calorie piece of chocolate. It’s a wash, right? Not so fast. You see, if John had just sat there instead of walking, he still would have burned some calories. Thus, the net burn is less than 100 calories, so if he did that consistently, he would gain weight. To make this even more complicated, research I’ve seen has shown that people who exercise tend to subconsciously move less during the rest of the day, partially offsetting the calories burned during exercise.

Recommendation: Manipulate calories to control the rate of weight loss. Do not try to factor in exercise, the goal of which should be progression. Only if you are losing weight too fast (I.e. over 2-3 pounds per week), adjust your calories upward.

Why You Can’t Lose Weight #5: Metabolic Defect

Prolonged periods of severe calorie reduction can significantly slow metabolism. A common scenario is a person goes on a 600 calorie-per-day diet and loses weight rapidly. However, soon weight loss will slow considerably and may even stop, as his body recognizes the lack of food and goes into a conservation mode. In order to continue losing, this person must further reduce calories, which will be very detrimental to long-term results. Usually, this is followed with rapid rebound weight gain with the same slow metabolism. Now he is worse off than when he started. To fix this, he may need to go through a prolonged period of fixing his deranged metabolism before he can even think about losing again.

Recommendation: Take it slow and do not reduce calories drastically. If you do plateau, assess your intake. If there is room to safely decrease your calories, then do so. Or, if you already are very low, make a short-term goal to increase metabolism. This requires meticulous food logging and involves very slowly adding food (i.e. 5-10 grams of carbs per week or two) with the goal of maintaining your current weight. Then, when maintenance needs are higher, a reduction will get you losing again.

Losing fat can be complicated, but if you’re dedicated to staying lean and in shape, it is definitely something that you can take on successfully.

Show 3 References

  1. Jonnalagadaa S, Mitchell D, Smiciklas-Wright H, Meaker K, Van Heel N, Karmally W, Erhsow A, Kris-Etherton P. Accuracy of energy intake data estimated by a mutiplepass, 24 hour dietary recall technique. American DieticAssociation Jour. Mar 2003. V 100;3.303-311.
  2. A significant number of practitioners (me included) believe TSH testing is inferior to examining free thyroid hormone levels (specifically the ratio of T3 to reverse T3). Treatment choices from low thyroid include the active thyroid hormone precursor T4 (Synthroid, Levothyroxine), active T3 (Cytomel, compounded sustained release T3) or combination pills (Armour). Again, this is a very controversial area and treatment should be guided by a knowledgeable health care professional.
  3. The metabolic component is important to discuss, but it shouldn’t be the first thought. People should have this evaluated by their primary doctor after demonstrating a failure of a disciplined approach to diet and exercise. Plus, being overweight or obese is not the only manifestation of hypothyroidism.


  • Daniel Barnhart says:

    Excellent article and recommendations. I do have a question though, I have seen many cut-offs for losing weight "too fast", I was curious if there are any papers or research into what are the indicators of this cut-off. 2-3 lbs seems too arbitrary when you can imagine that some people are over 400 lbs. I understand that range is likely for the average populous, but it can show that there must be some physical indicator (blood pressure, blood sugar levels, etc.) which indicate when you are actually in the "too fast" range.

    Again, thank you for the information and direction!

    • Charlie Seltzer, MD says:

      I agree with Marc. It has more to do with maintainability than what the actual number of pounds per week is. Really high rates of weight loss usually (but not always) reflect severe measures and the loss of things other than fat. If you're following a sound plan (not overly restricting calories or exercising excessively) and feeling well and the weight loss is pure fat, then the faster the better.

    • Marc Perry, CSCS, CPT says:

      @Daniel - That's a really interesting question. I think it's very tough to get that research because most research is done in terms of weight loss, not fat loss. From what I've seen, somewhere around 0.5% to 1% of your body weight in fat per week is achievable. We're talking pure fat, not water, muscle, or glycogen. I was featured as an expert in a Men's Health article which covers this topic here => How Much Weight Can You Lose In A Week?. As long as your energy levels are stable and you are getting enough sleep, I don't think it's possible to lose fat "too fast". If anyone else has anything to add, please do.

      • Stacy says:

        Hi Marc I have a real problem. I had people tell me for years how fat I was. Even by people I know who are fat tell me how fat I was. I got really mad at the fat people. So I ended up developing a full blown eating disorder. I lost 91 pounds in just under 5 months. How did I do it? Well I did 8 hours of cardio everyday, 7 days a week and only eating 500 calories per day. So how can I get my body out of starvation mode and lose the last 20 pounds? I want to get back in Track & Field and 140 pounds is what I weighed years ago when I was in track. I'm a woman that's 5'3" so 140 pounds is a healthy weight for my height. I would know how to maintain my weight of 140 once I get there. Thanks a lot.

        • Marc Perry, CSCS, CPT says:

          @Stacy - I'm sorry to hear you developed an eating disorder. I hear that from too many woman! It's literally an epidemic, but I digress. It does sounds like you are back on track now.

          I think following a specific exercise and nutrition plan can help you lose the last 20 pounds of fat. Regarding the nutrition, if you haven't done it already, I would eat a good 1,800-2,000 calories for several days and drink plenty of water. This may help restore your metabolic rate if it has dipped a bit. After that, it's a matter of creating a sufficient calorie deficit (my guess would be around a 1200-1400 calorie intake level) while keeping the protein relatively high and be sure to eat quality calories; whole, natural foods. I developed my own plan you can check out here => 8-Week Program.

          I think your goal of getting back into Track & Field is awesome!

  • James Forest says:

    Metabolic issues and defect are kind of scary words to combine in one post, but I'm glad to know there are contents like this out there. Thanks for sharing.

  • nadia says:

    thanks for the article -- very informative!

    i am working to lose fat and lose weight. i was doing well but have plateaued now for approx 2-3 months.

    initially, i was still seeing a decrease in inches so i just kept going and ignored the scale. but now, it seems that the number on the scale is rising, which is upsetting. i take in approx 1500-1600 cals per day (mainly fruits/ vegs/ proteins/ healthy fats; i log very carefully) and i follow a strength and cardio exercise plan that is progressing very nicely. i know i have a slow metabolism (every woman does in my family); i'm trying to increase my lean muscle mass to help combat that. i'm trying to sleep well (tough with an 8 month old at home and a job that can have odd hours, but it's way better than it used to be!).

    my concern is that i've carb-restricted so much that i'm now in category #5: metabolic defect. is that possible with a 1500-1600 cal/d diet? or is that only seen with extreme caloric restrictions?

    sorry for such a long post! thanks for taking the time to consider --


    ps. i love this website because of the great discussions and articles posted! please keep up the excellent work :)

    • Marc Perry, CSCS, CPT says:

      Hi Nadia,

      Few questions:

      1) How much exercise per day are you doing?
      2) How much do you weigh and how tall are you?
      3) How much fat do you want to lose?

      • nadia says:

        sorry mark -- didn't realize you had replied to me!

        to answer your questions:
        1) i do 15 mins of high-intensity intervals 3 times per week, 15 mins of superset based/ circuit-based strength training 3 times per week; warm-ups and cooldowns add another 5-10 mins per workout. i change my workouts every two weeks. mondays are a rest day. i've also bought a fitbit to try and increase my steps per day.
        2) i am 5'3" and i weight 201 lbs. i've lost 30 lbs since the end of my pregnancy. for the last four months though, the scale hasn't budged -- until this morning!!! so yay! something happened :)
        3)i would like to lose another 50-60 lbs. i know it'll take time (ie., 1-2 years) because it is a lifestyle change. i have zero interest in crash diets. i also know plateaus happen, and it's important not to give up, and to remain consistent.

        i saw a nutritionist and she suggested looking at my net carb intake (i had only looked at my total carb intake) and i was below her recommendation of 100-120 g/d (to avoid a ketogenic diet). so i upped my carbs this week (mainly from whole grains, beans, chickpeas, fruits and vegs etc) and all of a sudden, i am losing again :)

        thanks so much for the eye-opening article! if it wasn't for the article, i would never have thought to take a closer look at my carb intake --


  • Aleksandra Kopec says:

    Great article. There is so much emphasis on steady weight loss that I have seen people feel like failures at the plateau stage and revert to bad habits. Understanding the plateau is part of understanding long term healthy living. Thank you.

    • Marc Perry, CSCS, CPT says:

      Thanks, Aleksandra. Understanding that plateaus happen is so important. It's almost never a perfectly linear drop in weight/fat. The clients I've had who have been the most successful never let plateaus stop them from being successful and a few of the most successful clients I've had experience 1-2 plateaus.

  • David Dumas says:

    Excellent article, Dr. Seltzer. Thanks for posting it, Marc! I have lost 103 lbs over the past 43 months. I plateaud several times, and have broken the plateau again after a metabolism reset period of 2 months. I have approximately 50 lbs more to lose to achieve my ideal weight. Builtlean.com is a great help. Thanks.

    • Charlie Seltzer says:

      And please call me Charlie.

    • Charlie Seltzer says:

      Awesome, David. Thanks and congratulations on your success.

    • Marc Perry, CSCS, CPT says:

      Thanks for posting David and congrats on your success. Keep up the great work!

  • canali says:

    comes down mostly to calorie creep imo
    ieg not writing down what you're eating and/or not knowing the right amt of cals in each item as well as how many cals you should be taking in based on gender, age, height/weight, fitness goals and activity level.

  • Suzanne says:

    Hi went into severe metabolic problems and is having a very hard time coming out of it.
    I gained weight and severe water retention through running and not fueling enough for the activity I was doing.
    How long does it take to restore metabolic function back to a normal level?
    I only walk an hour a day at present because my body cannot handle high intensity exercises anymore. And fantastic post

    • Charlie Seltzer says:

      This will vary from person to person. In some instances it can take many months or even longer. But do not get discouraged, and you should make sure there are no thyroid issues. I would ask your doctor to check a full thyroid function panel, with TSH, free T3, free T4, reverse T3 and sex hormone binding globulin.

  • Charlie Seltzer, MD says:

    Thanks for all the feedback. I think it's important to note that while carbs get most of the bad rap these days, fat has more than twice the calories per gram than carbs. If you're following a carb restricted nutrition plan and are not seeing results, you may want to consider a moderate increase in carbs and a concomitant reduction in fat. Thus may result in better exercise performance, more satiety and more fat loss, though of course no one change is guaranteed to work for everybody.

  • John says:

    There seems to be a contradiction that I cannot wrap my head around: To build muscle, and therefore increase metabolism etc, every coach tells me to increase calorie intake, especially carbs and protein. However, to reduce body fat, everywhere is written we should reduce them. What is the solution to this contradiction?
    My experience has been that weight loss by reducing calorie intake has some effect on weight by shrinking muscles and a bit of fat right under the skin (especially on the legs and face), but absolutely none regarding intra-visceral lard which is where my doctor says I should lose it. Heavy exercising does the same, if not even more (increase in abdominal fat and decrease elsewhere). (To understand better: I have 20% fat, 90% or more of it inside the abdomen - Height 5'11, weight 175 lbs.- and have been working out intensively 5 to 6 x 1.5 hours per week for 4 years now.)

    • Marc Perry, CSCS, CPT says:

      @John - Charlie is welcome to add his thoughts, but I think the answer is actually pretty simple. Adding an extra few pounds of muscle increases calorie burn very modestly, maybe 20-30 calories per day (most research shows 1 pound of muscle burns somewhere around 7-13 calories per day) => http://www.builtlean.com/2013/04/16/muscle-burn-calories/.

      The goal in a fat loss program is to eat fewer calories than you burn to help your body burn fat while you maintain your muscle mass, which is done by eating ample protein and lifting weights. For more, you can check out the free Get Lean Guide I wrote. Your metabolic rate does not need to decrease much, but it will decrease a little as you lose body fat because you will have less body mass. That's expected as even fat burns some calories per day.

      So, in summation, focus on losing fat without losing muscle and don't worry about your metabolic rate.

      • Charlie Seltzer says:

        I concur.