Why do certain medications cause weight gain, with no changes?
I was referring to bad weight (body fat), as most people would be happy to have 10 lbs more muscle (your body looks better).
Medications can stimulate muscle growth, which can increase your weight without increasing body fat . . . with the side effect of requiring more calories for resting maintenance. Water retention is another common way to gain weight without actually getting fatter.
Why do certain foods cause weight gain/ loss, with the same calories? (think insulin)
What foods cause greater fat gain for the same calories? This magical food can cure world hunger, it's the perpetual motion machine of foods.
Why do hormones change weight gain/ loss?
Some hormones promote muscle growth. Higher percentage muscle mass on your body means that you need to eat more food to maintain weight. Some hormones promote water retention. Again, more weight (not necessarily bad weight - fat).
Some hormones trigger appetite changes which make you feel more hungry, so you eat more and are more likely to gain more fat.
Why does stress change weight gain/ loss?
Typically stress comes along with appetite changes. When you eat more or less you gain or lose weight.
Did you know that 3500 calories is not a pound? As in, if you eat 3500 calories too much, you won't gain a pound, and if you cut 3500 calories, you won't lose a pound. The body is amazingly capable of maintaining a "set point" in both directions.
If the body is so amazing at maintaining a set point in either direction, how does anyone's body weight ever change?
I can tell you for sure that this concept is bullshit. I used to regularly cut weight to get in a lower weight bracket for boxing tournaments. My regular body weight at the time was about 180, and I used to cut down to around 170 lbs . . . it would take about a month of an altered diet, and gave me a reach advantage over most people in my bracket.
At one point I tried gaining weight for a wrestling tournament. Several months of weight lifting and a lot of healthy foods, and I added about 20 lbs of muscle over six months.
It's not calories in vs. calories out for many people.
It's just not.
That doesn't mean you don't eat a healthy diet and get exercise, because both are awesome for you!!
It does mean that if you do both, and you are fit and healthy, who the fuck cares if you are 130 pounds or 150 pounds, or have a BMI of 24 or 26.
It also means: be kind, always. That 50 year old woman on the beach in her bikini with the spare tire - you don't know the path she walked to get there.
That 30 year old man who is 50 pounds overweight - you don't know that he just lost 70 pounds.
Don't be an armchair quarterback!!
First of all, BMI is bullshit. It doesn't take into account your muscle mass which makes it a stupid metric to pay attention to:
I don't judge people based on how they look. I grew up as a grossly obese little boy. I liked video games and reading in my room. My weight in grade four was the same as my weight when I was thirty . . . but I was a foot and a half shorter then. If I'd listened to the people pretending that the food you eat and the exercise you get don't directly control your body weight, I'd still be fat.