The Real Reason It’s So Hard to Lose Weight

[ ♪INTRO ] Losing weight is hard. Like, really, really, really hard. The overwhelming majority of people who try
to do it don’t succeed or end up gaining back what they lose, sometimes more. And that’s not just because pizza is amazing. It turns out your body actually pushes back
when you attempt to slim down. The fat stored in your adipose tissue is a
super energy-rich substance that your body can use in a pinch to fuel your cells. If you can’t eat for whatever reason, or
need a little extra energy to grow or reproduce, your body can turn to your fat — which is
why, from a survival perspective, having some fat is actually a good thing! Still, you’d think that losing weight would
be pretty straightforward: just eat less than you need, force your body use up some of its
fat, then go back to eating a normal amount when you’re the size you want to be. But the body doesn’t want to lose its energy
buffer — no matter how large or small it is — so when you cut calories, it reacts
in ways that ultimately make it harder to lose weight. A lot of the push back is driven by changes
to hormones. One of the most important is leptin, a hormone
secreted by your fat cells. The larger your fat cells are, the more leptin
they produce. So when you lose weight, leptin levels drop. Parts of your brain like your hypothalamus
interpret less leptin as starvation, and it jumps in and starts telling your body to conserve
energy and to eat more to rebuild those reserves. Other organs also use hormones to complain
to your brain about the decrease in fuel intake. Your stomach tells your brain it’s not getting
filled by increasing levels of the hormone ghrelin. At the same time, your pancreas secretes less
insulin, which regulates blood sugar, and amylin, which signals fullness. So when you cut calories, ghrelin levels rise
and insulin and amylin levels plummet, signalling your brain to increase appetite — making
you feel ravenous. In addition to changing how hungry you feel,
a suite of studies have suggested your brain responds to these hormonal changes by making
you more aware of all the food you’re not eating, and upping the pleasure you feel if
you do cave in. Meanwhile, the rest of your body becomes more
energy-efficient. For example, your muscles change where they
get their fuel. When your muscles need energy, they generally
use a mix of stored fat and circulating glucose. But when you’re on a calorie-restricted
diet, they rely more heavily on glucose, so they end up pulling more energy from the foods
you eat instead of those fat stores you’re trying to lose. They also make other small changes to become
more efficient — and so do other tissues in your body. Here’s the really annoying thing: this hormonal
starvation signal doesn’t stop when you stop dieting. That makes sense for leptin, since it’s
based on the amount of fat you have. But other hormones which generally respond
to food intake can stay on that slower production cycle even when you return to normal eating. And these hormones can stay altered for years. So even when you’ve stopped restricting
calories, your body continues to act like it’s being starved — which is a big part
of why people who lose weight often gain it back. To make matters worse, even regaining the
weight doesn’t shift your body out of energy-efficient mode. In general, the smaller you are, the less
energy you need to fuel everything. But it’s not a simple, linear relationship. How much energy you use per kilo at any given
body weight varies depending on whether you’ve ever been heavier or skinnier. And this effect could be clearly seen in a
2016 study which followed contestants from a televised weight loss competition for six
years. In particular, the researchers looked at the
participants’ resting metabolic rates: the calories their bodies burned at rest. It’s basically a measure of the minimum
amount of energy needed to keep a person’s cells running. After the 30 week contest, the 14 participants
lost an average of about 58 kilograms, and their resting metabolic rates dropped by about
610 calories per day. In the years that followed, though, they gained
back an average of 41 kilos, and their metabolic rates didn’t go back up accordingly. They ended up burning 500 calories a day less
than they should have at their final weights. Which means to lose weight in the future,
they’d have to restrict themselves even more than they did the first time around. Lots of other studies have come to similar
conclusions. After people lose weight, even if they gain
it back, their bodies simply use fewer calories per kilogram than similarly sized people whose
weight hasn’t changed. And that means they have to eat less to stay
at that weight than people who were never heavier, and they gain weight faster if they
do overeat. It’s not yet clear just how long all these
anti-weight-loss changes last — or if they ever completely go away. But not everyone experiences the same degree
of resistance from their bodies. Scientists are still trying to figure out
how our person’s genetics, the foods they eat, and other factors affect how a person
responds to dieting. But given how fiercely the body can fight
slimming down, it’s no wonder so many people struggle with it. Thanks for watching this episode of SciShow! And thanks especially to our patrons on Patreon. Your continued support is what allows us to
make educational videos like this one. If you like what we do and want us to help
us keep doing it, you can learn more about joining our patron community at [ ♪ OUTRO ]

100 thoughts on “The Real Reason It’s So Hard to Lose Weight”

  1. I see nothing wrong with any of this. If I want to lose weight it seems that I just need to up my activity. In that way I can prevent my body from going into starvation mode and it will continue to pull energy from both my fat and my food without all of the downside. In this way I can still eat my burgers and pizzas as long as my activities offset it enough.

  2. If you have been struggling to stay slim and toned like I have my entire life you should check out the Leisure Diet method. So far I am 2 weeks in and have lost over 7 pounds without changing my diet or exercise. I found this solution at

  3. Has anyone else tried the Leisure Diet? A close family friend of ours highly recommended it to me after I notice how much weight she was able to lose over the last couple months. I think I am going to order my free bottle from and see how it goes.

  4. I know it’s still winter but I can’t stop thinking about how much weight I want to lose by summer time! A good family friend of ours highly recommended the Leisure Diet method to me. After seeing her lose so much weight after the last few months I think I am going to take the plunge and order my free bottle from

  5. If you have been struggling to stay slim and toned like I have my entire life you should check out the Leisure Diet method. So far I am 2 weeks in and have lost over 7 pounds without changing my diet or exercise. I found this solution at

  6. So basically simple, go on a diet, eat less. When you lose the weight you want, dont go back to normal eating and stay eating less then before you lost weight. Check yourself on scale daily and if you see your putting on weight, eat less, if you're still losing, eat a tad more.

  7. I lost 30 kg of my weight almost without having a strict schedule of exercise or diet! I did that by changing my life style and cutting sugars almost entirely. While also making sure to stay active like cycling for long hours even if it is not intensive or walk an extra distance just to push myself. I did this over 2 years and it completely changed me. Now am still struggling to remove my belly but I lost a great deal of fat and I need to push more! Sugar is one of the main culprit!

  8. I once went through a major depressive jag for about 8 months, and – having no appetite whataoever but knowing I had to eat something at least 1x a day – forced myself to eat a few ounces of food everyday in the form of a bit of tuna or salmon and a couple pieces of veggies. Rarely, a bit of dried fruit. I did not exercise, in fact, I was more sedentary than ever. I still lost the 35-40 pounds I was overweight for my height/body type. I didn't even notice until someone asked me if I'd lost weight.

    Contrast this to a very overweight former coworker who exercises daily but also daily eats large meals of fastfood 1x-2x a day, who hasn't lost weight (and I think might actually have been gaining).

    Point is, I ate less food and what I did eat was healthy. That's it. I don't recommend the extremity of the Depression Diet, but simple truth is that unless you have a medical condition, there is no way around "eat less, eat healthy" to lose weight for most people.

  9. I ate nothing but Romaine, canned tuna, and some lemon juice for a year to drop 50 pounds, and was hungry all the time. I gained back 30 pounds over the following 5 years after returning to a healthy, but more normal diet, without a lot of treats. I also walk 5 to 7 miles a day. My clothes fit better now than before I lost the 50 pounds, but trying to take off more than 5 pounds is a real struggle. I guess I’m what a farmer would call an “easy keeper” (a herd animal that doesn’t eat a lot, while maintaining a good size.). 😕

  10. I ended up losing 48 pounds after moving out on my own, cause ADHD and other factors make cooking annoyingly impossible, and eating a chore. And the ADHD meds prevent feeling hunger so sometimes I just forget to eat all day until I get up to do whatever and suddenly realize I'm dizzy. I was nearly 200 pounds before, so while it wasn't intentional at first, now I'm getting paranoid at the thought of gaining it back… I lost it over a year or so, and it seems to be staying off but…. I don't want to go back to that.

  11. Sources would be helpful. I wonder if the formerly obese groups that metabolize differently continue to eat a higher volume of artificial sweeteners. Research has shown that most artificial sweeteners cause insulin production, which then causes triglyceride production. This could account for those missing calories. Seems more likely than some form of metabolic memory.

  12. Personally, I've struggled with my weight all my life. Nothing really ever helped. I was sad and felt hopeless until I came across the red tea detox and decided to try it out! Figured I had nothing to lose! So why not.
    And my was I amazed! Within 2 short weeks I lose 10 lbs… Mind you I was 230 when I started.
    for more about red tea pls g o ( w w w .redteaidea .gq ) remove the space before .gq for access

  13. This is definitely a place I'd support gene editing on ourselves to make our bodies more suited to the (relatively post-scarcity) lives we lead today (as opposed to the lives our pre-technological, pre-agrarian ancestors led) because it really does annoy me that my body cannot remember having overeaten the day before and that it has no concept of its levels of reserves.

    It might be nice if the brain viewed its resources more in terms of a fuel tank (still have a half a tank of gas and two jerrycans of reserves…we're good for a while…cancel hunger alert…let's use what we have up first) rather than what feels like a timer that begins after every meal to signal hunger X number of hours later even though that entire pizza you ate is plenty sufficient for an entire day.

  14. So how were these people physically able to have a lower resting metabolic rate? Did they have a lower body temperature? Less brain activity? Less muscle activity? Less muscle mass?

  15. I know everyone thinks this is bad and it's portrayed with a negative tone. But through my life experience I BELIEVE THIS IS A GOOD THING!

    For about half a year I've been intermittent fasting about 18-22 hours a day with maybe 2-5 days off a month where I just eat whenever. I had already started noticed on my own that my body was getting very sensitive to losing and storing weight. it's crazy but it's fine. Because guess what? I can eat 2 simple meals a day and feel comfortable in my stressful day 2 day, because like SciShow said my resting MBR is lower. It's great! I use less energy, I'm more efficient, I spend less, I cook less, I save time.

    But you store fat more easily you say! Yes! And that's also fine, because now if I ever need energy I can just tap into those fat stores instead of having to need energy from more food and more potential glucose which I don't need anymore. It's Great!!

    If you still think this is bad, my wild guess is it's because there is a value in most of our cultures that we should be able to eat as much as we want and not put on weight. You might be buying into that. You want everything and everything, all day, at no cost. (Sorry if I sound like a fitness coach/army sergeant right now) but eating less and still being able to function more efficiently as human beings should be not be frowned upon and looked at with a more functional perspective.

  16. This is why feeling full on healthy foods is so important. Drinking a large fruit and veggie smoothie and walking 60 minutes per day has kept me 130 pounds at 5'6 for years.

  17. Videos like this are what "Anti Fat Shaming" advocates will show me,
    while chucking down a chocolate cake, Large Pizza, Burgers, Fries, Doritos and buckets of Pepsi.
    That's not how fitness and losing weight works.

  18. This is sadly true. Many years ago I lost 20 pounds through diet and exercise. I’m a small person so that was a lot. Last year I put on 7 pounds after a tragic loss. I tried to lose it again following the exact plan I used to lose the 20. It didn’t work. Even when I upped the exercise and cut my food intake to half it still didn’t work. I since have accepted that my body simply likes those extra pounds and in order to lose them I’d have to cut them out. 😕

  19. Just watch this video people and start ketogenic diet and Intermitten fasting to lose weight. Its not all about restricting calories is much more- trust me!

  20. Surgery and hormone manipulation are the only way for those that don't want to meticulously measure calorie intake for the rest of their life.

  21. This video is basically saying it's impossible to lose weight and keep it off. Is this true? I mean scientifically speaking is it impossible to lose weight? You need to clear this up!

  22. Good example of why crash diets and extreme measures are a bad idea. General rule, if it makes a popular TV show people want to watch, you shouldn't be doing it. Slow and steady wins the race. It likely took you a long time to build up all that extra fat, and it will take a long time to safely lose it. A 500-1,000 kcal per day deficit to lose an average of 1-2 lbs of bodyweight per week over the long haul is the way to go.

  23. I am glad that I found out this video because I knew that weight loss is a hormonal balancing act—which makes me wonder that women struggle more than men in regards to hormones during their spikes or changes throughout their lives.

    Although it may sound disheartening, it raises awareness of that extra distance people have to make in order to find, or rather wait, for their results depending on whether they’ve reached or passed their limits.

    Since I have started intermittent fasting, I did realize a subtle increase in weight, but my body has became somewhat toned.

    I am working out at least 4 times a week, and not going heavy at the gym as to avoid tiring myself out, and now I have reached that 16 hour mark for fasting, since I was earlier adapting to just 12-14 hours.

    I still have a month to go to see some results, but again this video raises awareness that I have to commit to years to see results—but that doesn’t dismay me, but rather focused my efforts to other things rather than eating.

    Thank you for this video—oh yes CHALLENGE ACCEPTED.

  24. The funny thing is that i eat a lot of fats and protein, and with the strength and endurance exercise ive been getting lately, ive been steadily losing weight. Im not trying to, nor am i doing anything that would logically lower it. I guess my body is running on higher metabolism right now due to something in that life style. Before i did the exercise i was almost obese on a bmi chart(tho im built like a brick, runs in my family) and weighted 230 lbs. at 6'1. Then i started working on building muscle mass and im losing weight without actively trying. I guess its the activities, not the diet.

  25. "Exercise" doesn't do it. Weight training with correct timing of nutrients allows one to much more easily lose fat. Think bodybuilders. They can lose tons of fat and keep their muscle because they do both food intake and exercise correctly. You should include complete info, not just the quips you're spouting.

  26. I've been stuck at 150 for years. Years ago I was 180. I've been going to the gym for 5 months now. 4 days a week. Eating less and working out an hour. My body has not changed…and its annoying asf. And even more annoying that another person can do this and they lose weight like nothing

  27. Professional anorexic here. For those of you who want weight loss tricks, i found it helpful to cut out processed foods, focus on calories in and calories out, and ingesting things that boost metabolism (such as coffee and green tea). I lost 30 lbs in 1 month, and although it wasn't healthy, it worked.

  28. Insulin is the main player in making you fat – when you eat excessively or eat sugar insulin is elevated. Just by reducing or abolishing sugar and refined carbohydrates from the diet, insulin drops! Reducing snacking also lowers insulin. Anyone with too much body fat usually has elevated levels of insulin (hyperinsulinaemia). The role of body fat is as an alternative fuel source when the body is starved of sugar, not calories! Prove me wrong pls

  29. It seems like its really really important to not gain the weight in the first place. People need to become more proactive about avoiding obesity. Even if you think "Ive always been able to eat whatever I want and I never gain weight anyways" its probably a good idea to be mindful.

  30. But let’s not kid ourselves – overweight people don’t eat more because their bodies are ”starving” 👀

  31. they struggle with it because they try crash diets. If you diet and start eating the way you did before you tried to lose weight you're going to put that weight back on. If you want to lose fat and keep it off your nutrition has to be part of a lifestyle.

  32. What if you keep your caloric intake roughly the same (but like, slowly reduce the amount of carbohydrates and sugars you eat) while increasing your energy consumption? Then again, that, too, would need to be a permanent thing.

  33. its that and also how often do you eat?
    if you eat between breakfeast, diner and than souper, you will certainly gain more weight BUT, if instead of eating between you would drink water of juice instead, it would make a difference
    or just don't eat between those times,

  34. I gained about five pounds over the past two months because of extremely high stress at school. After spring break, I’m feeling much better…but I’m terrified that I won’t be able to lose those pounds. I cut many calories from my diet (desserts, candy, and every beverage other than water), but I’m not seeing results. It’s really really scary because I’ve never struggled with weight in my life. So this video is pretty discouraging tbh!

  35. So it basically comes down to your determination in loosing weight. If you come back to unhealthy or excessive diet you will gain weight even more. World is filled with companies and their 'products' for fast and easy weight loss because people would like to loose weight without making them self uncomfortable. Many diets for 'super fast' weight loss work but only short term, and please be careful and take some random peoples recommendations about diet X with grain of salt – there are countless companies which sell opinions/comments on online stores, review sites, forums etc. If you know someone who always complain that he/she can't loose weight, I'll bet you they still eat more then they should, and probably avoid sport. If you change your diet and go to gym or run, ride bicycle etc. you are bound to loose weight, genetics will affect how fast and how much you will loose. Then you have to keep it up even if you are fit, because yo-yo effect is real 🙂

  36. Are you aware that in case you completely refrain from your favorite carbohydrates all the time since you assume they’re damaging or that you believe that they’re the factor for all of your extra belly fat, it may possibly be detrimental for your hormone amounts not to mention wreak havoc on ones own metabolic process? Find out more helpful pointers in this article

  37. This should have ended with possible solutions to overcoming these issues; tricking the body, so to speak. Instead y'all give me this depressing news and then go "thanks for watching!"

  38. There are a lot of things one can do to lose weight and eating less and moving more are two important steps to achieve that. for more please visit here

  39. Immediately after I performed my investigation in this particular “Yamzοkο Weebly” (Google it) diet plan that has been brought in by a buddy who shed excess fat, I shed about 9 pounds as well. I truly do consider it helped boost that weight-loss as well as fat burning. And i also am eating healthy foods right now. .

  40. So many incorrect and/or misconstrued statements in this video. I really like Sci Show but this video should really not have been done without better research. A better explanation about how all this stuff works can be found by watching some of Jason Fung's videos/interviews or by checking out the channel "What I've Learned". He has a great video on how fat loss really works(I forget what it's called). I'm not saying they're the best videos, just the ones I can think of off the top of my head, and they are miles ahead of sci show in terms of accuracy.

  41. For me taking adderol helped me lose weight. It makes you stop going to the refrigerator. Not the healthiest solution, but it is all that worked for me.

  42. Loosing weight is difficult if you are on a high carbohydrate diet (AKA American diet). Try Keto and you'll lose weight without having to starve yourself.

  43. I have lost 5 kilos since last month and thought this video could help me. But it just demotivated me 🙁 . I don't want to give up on my weight lose journey this time sigh

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