What is the science behind losing weight?

  • #1
AchillesWrathfulLove
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I was 302 pounds now I am 271 pounds after three weeks of consistent dieting. I am wondering why have I lost weight? I eat basically one massive tuna sandwich a day and that is it and I eat everyday at the same time which is 12 o'clock. Also how much of this weight was water weight? Because I read online that you lose water weight first then you lose fat.

Thank you in advance.
 

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  • #2
Evo
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I was 302 pounds now I am 271 pounds after three weeks of consistent dieting. I am wondering why have I lost weight? I eat basically one massive tuna sandwich a day and that is it and I eat everyday at the same time which is 12 o'clock. Also how much of this weight was water weight? Because I read online that you lose water weight first then you lose fat.

Thank you in advance.
We don't know. You normally lose weight when you consume less calories than you burn. Medications, hormones, etc... can add to the complexity.

I don't understand, you said "after three weeks of consistent dieting. I am wondering why have I lost weight?" Seriously?
 
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  • #3
AchillesWrathfulLove
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I mean like dieting like eating healthy, I stop eating junk food and only eat Tuna Sandwiches. Do you know how many calories the body is burning?
 
  • #4
russ_watters
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I mean like dieting like eating healthy, I stop eating junk food and only eat Tuna Sandwiches. Do you know how many calories the body is burning?
Google: calorie burn calculator
 
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  • #5
AchillesWrathfulLove
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Thanks for that. 2600 is my calories burnt a day.

Do you know why fatter a person get the more calories they burn? Cause when I add higher values for weight the calories burnt also increases. Also how accurate are these calculators?
 
  • #6
russ_watters
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Do you know why fatter a person get the more calories they burn? Cause when I add higher values for weight the calories burnt also increases.
When you are bigger/heavier, everything you do - including sleeping - takes more effort than when you are smaller/lighter.
Also how accurate are these calculators?
Not very.
 
  • #7
Evo
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Thanks for that. 2600 is my calories burnt a day.

Do you know why fatter a person get the more calories they burn (exception to what Russ posted)? Cause when I add higher values for weight the calories burnt also increases. Also how accurate are these calculators?
It is not true that the fatter a person gets the more calories they burn. I don't know where you read this. What calculators? Have you consulted a doctor about your weight loss? How much weight do you intend to lose? How do you know how many calories you burn in a day?
 
  • #8
AchillesWrathfulLove
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It is not true that the fatter a person gets the more calories they burn. I don't know where you read this. What calculators? Have you consulted a doctor about your weight loss? How much weight do you intend to lose? How do you know how many calories you burn in a day?

I use this one to find out how many calories I burn https://tdeecalculator.net/

and I didn't read it anywhere I just input higher and higher weights and it gives more calories burnt

also my doctor is one who suggested I lose weight and gave me an appetite suppressant but i know all the meds in the world won't save me if i don't improve myself

i also use to weigh 85 kilograms at 17 and I am 22 now so I want to get back in that shape I was.
 
  • #9
jim mcnamara
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This will answer your question, it is designed for people who are not scientists. Basically, if you take in less energy than your body needs, the weight you lose is from a biochemical process called respiration - the breakdown of fat into water and carbon dioxide to balance the energy deficit.
 
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  • #10
Evo
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I use this one to find out how many calories I burn https://tdeecalculator.net/

and I didn't read it anywhere I just input higher and higher weights and it gives more calories burnt

also my doctor is one who suggested I lose weight and gave me an appetite suppressant but i know all the meds in the world won't save me if i don't improve myself

i also use to weigh 85 kilograms at 17 and I am 22 now so I want to get back in that shape I was.
There actually are meds that will make you lose weight, but they are not widely known. It's a side effect. They are not advertised as weight loss meds, but definitely will make you lose weight. I'm on one for pain, and I can't stop losing weight. I'm on a med that causes weight gain, and it has overridden it and then some. You just feel full all of the time, so don't want to eat. I have to force myself to eat.
 
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  • #11
AchillesWrathfulLove
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This will answer your question, it is designed for people who not scientists. Basically, if you take in less energy than your body needs, the weight you lose is from a biochemical process called respiration - the breakdown of fat into water and carbon dioxide to balance the energy deficit.


Thanks so is peeing a lot maybe a good sign you are losing fat?
 
  • #12
AchillesWrathfulLove
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There actually are meds that will make you lose weight, but they are not widely known. It's a side effect. They are not advertised as weight loss meds, but definitely will make you lose weight. I'm on one for pain, and I can't stop losing weight. I'm on a med that causes weight gain, and it has overridden it and then some. You just feel full all of the time, so don't want to eat. I have to force myself to eat.

I will ask my doctor if he knows any so I can try taking it, thanks.
 
  • #13
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Penn Gillette had a radical diet eating potatos only and lost 100 lbs.



As others have mentioned here, you should eat less than the calories you burn, exercise to stay healthy and avoid carbohydrates so that you body will get into the ketosis cycle. This is not easy or fast to do but it is the best course because after you reach your weight you must keep up the same regimen for life to stay slimmer.

Fad diets help you get your weight down fast and then provide a second regimen to follow to maintain your new weight but it’s a different sequence of steps and is harder to follow without a lot focused attention.
 
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  • #14
russ_watters
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It is not true that the fatter a person gets the more calories they burn. I don't know where you read this. What calculators?
Evo, every calculator of calories burned I've ever seen shows this. It really should be obvious as to the reasons why: everything you do requires more energy output to do it when you are heavier. For example, when a heavier person is walking up stairs you are lifting more weight up the stairs; more output energy requires more input energy. Did you misread the statement?
 
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  • #15
Evo
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Evo, every calculator of calories burned I've ever seen shows this. It really should be obvious as to the reasons why: everything you do requires more energy output to do it when you are heavier. For example, when a heavier person is walking up stairs you are lifting more weight up the stairs; more output energy requires more input energy. Did you misread the statement?
You are right, I was just thinking beng fat didn't burn more calories without thinking of the added exertion.
 
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  • #16
Evo
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Penn Gillette had a radical diet eating potatos only and lost 100 lbs.



As others have mentioned here, you should eat less than the calories you burn, exercise to stay healthy and avoid carbohydrates so that you body will get into the ketosis cycle. This is not easy or fast to do but it is the best course because after you reach your weight you must keep up the same regimen for life to stay slimmer.

Fad diets help you get your weight down fast and then provide a second regimen to follow to maintain your new weight but it’s a different sequence of steps and is harder to follow without a lot focused attention.

These diets are bad for your kidneys. Foods high in potassium are bad for your kidneys.
 
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  • #17
ZeGato
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I was 302 pounds now I am 271 pounds after three weeks of consistent dieting. I am wondering why have I lost weight? I eat basically one massive tuna sandwich a day and that is it and I eat everyday at the same time which is 12 o'clock. Also how much of this weight was water weight? Because I read online that you lose water weight first then you lose fat.

Thank you in advance.

You're consuming much less calories than the ones you are using up. I would seriously re-evaluate the diet you are doing though - by only eating a sandwich a day you're missing important nutrients, which may harm your health.
 
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  • #18
Stephenk53
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Remember if you lose weight too quickly then your body will go into survival mode and will cause you to more readily regain weight once you are done dieting. Also if you lose weight too quickly it can severely harm you.
 
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  • #19
Ryan_m_b
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Thanks for that. 2600 is my calories burnt a day.

Do you know why fatter a person get the more calories they burn? Cause when I add higher values for weight the calories burnt also increases. Also how accurate are these calculators?

The human body expends energy to stay alive, we measure this energy with a unit called Calories. The bigger we are the more of us there is and the more calories we need, also being active uses more calories as our body expends more energy. You can think of this like a car: a smaller car weighs less and needs less fuel to cover a journey than a heavier car. Also a car that drives faster or drives more often needs more fuel.

We get our energy from food and we can measure how much many Calories (that is how much energy) is in our food. If your body burns 2600 Calories a day then you need to eat 2600 Calories a day. This is like how if your car needs a gallon of gas a day you need to put a gallon of gas in the car each day. If we eat more Calories than we need the body doesn't waste them, it stores that chemical energy as fat. This would be like putting a canister of gas in a car trunk, even though the gas tank is full. If you burn 2600 Calories a day but are eating 3100 Calories your body makes 500 Calories of fat every day (about 70 grams, or 2.5 ounces). If you eat less than the amount of Calories you burn then to make up for it your body will burn the fat instead. In other words: Eat more energy than you burn = Gain weight. Eat less energy than you burn = Lose weight.

People who diet are eating less energy than they burn each day so they lose weight. Exercise makes us use more energy so it is also a good way to lose weight. There are many other factors beyond this; hormones, nutrition, how severe the Calorie deficit is (eat too few calories and your body will think you're starving and lower your metabolism, slowing the weight loss) etc. You can read a lot online about dieting but it's best to talk to your doctor about all the options. They will have knowledge (and probably literature) that you can trust, whereas there are a lot of scams and dangerous fads online.
 
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  • #20
CWatters
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I was 302 pounds now I am 271 pounds after three weeks of consistent dieting. I am wondering why have I lost weight? I eat basically one massive tuna sandwich a day and that is it and I eat everyday at the same time which is 12 o'clock. Also how much of this weight was water weight? Because I read online that you lose water weight first then you lose fat.

Thank you in advance.

The physics is down to Conservation of Energy. If you expend an excrete more energy than you consume you will loose weight.
 
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  • #21
DaveC426913
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Remember if you lose weight too quickly then your body will go into survival mode and will cause you to more readily regain weight once you are done dieting. Also if you lose weight too quickly it can severely harm you.

Yes. The healthy number I have heard is more like a pound a week. Losing too much too fast can be risky. It also may not stay off.

Also, whenever one loses a lot of weight rapidly, it is more often due to water loss. Ten pounds of that might be water.
 
  • #22
jrmichler
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Thanks so is peeing a lot maybe a good sign you are losing fat?

No. It's a sign that your hydration level is changing. You are losing water. You are far better off to eat a balanced diet of about (your doctor can recommend a better number) 1600 to 2000 calories per day. That should give you a sustained weight loss about one pound per week, and keep you healthy. Aerobic exercise is also good.

Crash dieting commonly leads to significant weight loss, followed by "thank goodness that's finished", followed by a gradual return to previous bad habits, followed a year or two later by weighing more than when you started. I don't have specific references for that statement, but I've seen it in articles referencing peer reviewed studies.
 
  • #23
Evo
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I think we are heading into giving medical advice. To the OP, consult your doctor. We are not qualified to give dietary/nutritional advice, so thread closed.
 
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