Does metabolism actually affect caloric intake?

[fsaekar]

Is "high metabolism" actually an attribute one has apart from 1) physical activity, 2) the rate at which food is consumed over the day, and 3) the types of food one eats (some are easier to digest than others), or is it merely the attribute that takes the blame (or praise) from those who think they are getting enough calories to gain weight but actually aren't?

If the former then metabolism is really nothing more than inefficient digestion, it would seem, which is hardly enviable. And if the latter then the answer to "why do I have a high metabolism?" has little to do with genetics and everything to do with the 3 factors I listed earlier, namely amount of physical activity.

Seems like the general public thinks that metabolism is an inherited trait that some have and some don't. If my understanding of metabolism is correct, I want to tell these people, "Stop making excuses. You're just like me---when you take in more calories than you need you gain weight. Eat right and exercise often and you'll find that you can EAT MORE without gaining weight!"

Anyone with some nutrition knowledge want to add their thoughts?

[atypical1]

It's a combination of all of those things really and you'll need to include age in there. Some people just naturally have the ability to burn calories at a higher rate than others. Also as you age your metabolism slows down (ask me know I know...).

But, you are spot on when you say that the key, regardless of your metabolic rate, is to eat right and exercise. But it's very easy to just blame it all on genetics. If you know you don't burn calories that fast then you simply need to make sure that the calories that you do eat really count and are "good".

james

[fsaekar]

Thanks for the thoughts. But even when you speak of metabolic RATE, you would agree that at the end of the day the only thing that matters is needed calories vs actual calories consumed? For example, at rest I burn 100 cal/hr and you burn 50 cal/hr. Therefore I need 2400 cal/day and you only 1200. I'm still going to gain weight if I eat >2400 cal regardless of my metabolic rate, and likewise you for >1200 cal, no?

Like I said, the only alternative seems to be digestive problems. But Is this a serious factor in a lot of people?

Another consideration... is it true that some foods are more likely to be used as energy (as opposed to being stored)?

[MikeD]

This will sound like a "friend of a friend" thing, but I've read that people of different bodytypes who were given the same amount of cals over their maintenance didn't gain the same amount of weight. Meaning, the two people of different body types overate the same amount, but one gained weight and one didn't, which throws off the law-of-thermodynamics thing.

But that's just trivia, really. I'm terrible at figuring out diet.

[Bman1]

I think one other factor that hasn't been mentioned is what I'll call "digestive efficiency". Each of us will absorb slightly different amounts of calories from our food depending on the type of food we eat, what we eat with it, the types of bacteria in our intestines, etc., etc. For example, if I have a relatively inefficient digestive system, I might extract only 85-87% of the total calories from the food whereas someone else might extract 93 or 94% of the calories. Even though we ingest the exact same number of calories, I might not gain weight while the other person will.

A corollary to each individual's "digestive efficiency" is that how the food is prepared will effect how well the calories are absorb. For example, it has been fairly well established that people abosorb about 90% of the protein from cooked eggs and only about 50% from raw eggs (the rest being pooped out).

So you have both an individual's digestive efficiency and the digestability of the food and how it is prepared that will effect one's "metabolism". Just another reason why the estimates of calorie needs are just estimates and need to be tweaked based on your actual results.

[itsbruce]

An important note to add to the digestive/metabolic efficiency is that the fitter and leaner you are, the more efficiently you process food. Obese, inactive individuals have low digestive efficiency - they take in so much and use so little that their bodies simply don't need to be efficient. Active people with moderate diets, on the other hand, have trained their bodies to make the maximum use of what they consume.

2 things to take from this which are relevant to the thread:

1. Obese people who claim to be fat because they have "slow metabolisms" are kidding themselves; their bodies actually process food more quickly than others - they have to, because of the rate of ingestion. They get fat because they eat too much and do too little. It's that simple.
2. Those of us who are active and have moderate diets actually risk putting on more pounds of fat from eating a box of chocolates than an obese individual; we've trained our bodies to make maximum use of what we ingest. If you eat the occasional treat and don't put on weight, it's because it's occasional, not because you burn it off so quickly. In developed societies, very few people, other than professional athletes in the most demanding fields, burn so much energy in their daily activities that they can chomp through fatty, carb-loaded snacks and not pay the price.

[thefinalsql]

I pick #3, but not for the reason you list, but rather insulin resistance. I think your level of insulin resistance matters more than anything else in regard to your metabolism.

[Teak]

I tend to side with the 'inherited metabolism is BS' argument. Anecdotally, if you talk to your friends who have always been skinny and say things like 'i eat whatever i want, whenever i want,' about their actual diet, 9 times out of 10 in my experience you'll find that they just eat very little.

IMO it's similar to the Atkins effect where people believe they're not watching what they eat, but they just 'happen' not to eat very much naturally.