- Brian Bender, PhD
What is Metabolism? [Infographic]
When it comes to dietary health, metabolism usually enters the discussion. But what is it? Can it change? Does everyone's metabolism look the same?
What is Metabolism?
At a high level, metabolism constitutes the chemistry that makes life happen.
One example is digestion. After you eat, your body needs to convert that food into fuel. To do so, your body gets to work breaking the food down and converting the food molecules into other molecules useful for things like running, jumping, and, oh yeah - breathing.
Here are the three major categories of metabolism to give you an idea of where your calories go.
Speaking of breathing, your basal metabolic rate, or BMR, is your "minimal cost of living."
That means, you need to burn these calories for your body to function properly. Think of your organs - heart beating, brain thinking, stomach digesting. All of these things happen in the background, and they all require energy (i.e. calories).
Your BMR is often your biggest source of caloric expenditure throughout the day (unless, maybe, you're training for a marathon - or work as a lumberjack).
This _can _change. And it does, particularly when your weight changes. Losing pounds will lower your BMR, and gaining weight will increase your BMR. In fact, this is part of the reason why dieters sometimes hit a _plateau _when shedding pounds - they must readjust to a lower BMR.
Body composition is another factor than can change your BMR. Hitting the gym can add muscle, which has a higher metabolism than fat and could help offset a reduction in metabolism caused by a lower weight.
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And there is some variation among the population despite similar body sizes. Likely some combination of genetics, epigenetics, gut flora composition, and environmental stressors, this variation is one key component of personalized nutrition.
2. Physical Activity
Moving burns calories. No big surprises there.
But odds are, you burn less than you might think you do during these activities. The infographic below highlights a few major activities and their rate of calorie burn.
So is it still worth it? Absolutely. In addition to burned calories, exercise still works wonders for things like cardiovascular health, mental health and stress reduction, bone health, lean-muscle development, and so on.
3. Diet-Induced Thermogenesis
The title is fancy. It simply means that digesting calories requires you to burn calories.
Yes, you read that right. Acquiring calories requires you to burn calories.
And not all food requires the same amount of calories to metabolize. Interestingly, the macronutrients you consume are metabolized differently.
Granted, this isn't a major source of caloric expenditure, but it is the third and final major category when considering diet and metabolism.