“Is there really such a thing as fast and slow metabolisms?”
We all have the one friend who seems to eat whatever they want, never gaining a pound. Annoying, right? On the other hand, we’ve all heard the people who claim they gain weight simply by just looking at a carb, and only lose weight if they significantly drop their calories. So, is there anything to this?
Is there really such a thing as fast and slow metabolisms?
Simple answer? YES, there does seem to be some difference in metabolisms between these types of people.
More thorough answer? It’s not the metabolic rate specifically, but the ADAPTIVE piece of their metabolisms. Let me explain further…
There was a study done by Hollstein et al where individuals were placed in a metabolic ward and were fasted for 24 hours. Then, the same participants were “overfed” with a low protein diet. The study ended up classifying individuals into two different groups based on how their body responded to being both overfed and underfed.
1.) The “Spendthrift” metabolism group (you can think of this as the “fast”metabolisms group). This group had a metabolism that was more responsive to being both over and underfed. When they were overfed, their metabolisms revved up and burned more calories. When they were underfed, their metabolisms did NOT drop significantly. This is the type of person who has an easier time losing weight and doesn’t gain weight as quickly.
2.) The “Thrifty” metabolism group (you can think of this as the “slow” metabolism group). This group had a metabolism that was more “thrifty”, meaning it was more efficient at using calories. They burned significantly less calories when they were underfed and they did NOT burn much more when they were overfed. This is the type of person who has a harder time losing weight and gains weight easier.
Here are the specifics, if you’re curious:
An important piece to know about this study is that both groups of people actually had similar weights and body compositions at baseline. It CANNOT really be concluded that people have “fast” or “slow metabolisms.” But it CAN be concluded that individuals have different adaptive responses that can make weight loss harder for some and easier for others. You could have two people who both maintain their weight well on 2000 calories, for example. One person may be able to drop to 1700 and see great weight loss, while the other person may have to drop to 1500, for example, to see the same rate of weight loss. On the other hand, one of them may be able to increase their calories up to 2200 and see no fat gain, while the other person, with a more efficient metabolism, might gain fat by increasing to 2200. Essentially, this study just further clarifies how complex our bodies and metabolisms are. And again, this is why online calorie calculators are really just a starting point! Even coaches cannot know for sure how your body will respond to a certain caloric amount. However, having a coach to help monitor data and make changes based on how your body responds can be very helpful!
Some practical tips:
No matter which group you fall within, muscle makes us all more metabolically flexible! It’s just a fact. So lift weights through ALL phases of life!
If you feel that you fall within the “thrify” metabolism group, you might be someone who needs a higher step count during deficits. Try increasing your step count by 2-3k day per day from your baseline when dieting. This can help offset those downregulations that occur when you diet. As a coach, I have seen this be a gamechanger for those who have a harder time losing weight.
Most people truly are “average”when it comes to progress rate, but society, social media, etc makes us feel like we’re below average. Have realistic expectations when it comes to both deficits and maintenance.