Key Topic

  • Assuming decent knowledge about fat loss. If not, check out our other content e.g. the “Nutrition for Fat Loss” Blog post or 3 part podcast series we have.

Actual Loss in Body Size Leading to Reduced Energy Expenditure

  • Our body requires energy (calories) to fuel its daily functions. 
  • When total body mass reduces, typically it requires less energy.
  • Directly, this literally means fewer calories are burned for things like maintenance of muscle tissue or other passive functions.
  • Indirectly, this means fewer calories are expended during things like walking around during the day.

Metabolic Adaptation

This is the main one a lot of people will be interested in. Our metabolism is adaptable. If we eat fewer calories, our metabolism can “slow down.”

It does this by downregulating certain functions, usually starting with lower importance functions.

Two good things about metabolic adaptation are that:

1) It often isn’t that big of a deal. It rarely accounts for more than a couple of hundred calories per day difference. 

2) It goes in both directions. When you eat more calories, your body adapts in the other direction. It also does not take that long for things to return to normal too. 

Incidental Movement

  • When we are consuming higher calories, we naturally tend to move more and burn more calories.
  • There is actually pretty huge variation between people when it comes to calories burned through incidental movement.
  • When people are on lower calories for an extended period, often their incidental movement decreases.
  • Some of this is completely unintentional, such as naturally fidgeting less or moving slightly slower.
    • Other times it is just due to feeling fatigued. For example, somebody might have less interest in going for a walk if they feel fatigued. 
  • This is actually a large reason why a lot of bodybuilding coaches have step targets for their clients.
    • Doing that partly offsets this issue.

Thermic Effect of Food 

The thermic effect of food is relevant in a few ways.

  • One is that our body burns calories in the process of eating and digesting food. It’s often around 10% of total calorie intake that gets expended in this process. But it depends on variables such as protein and fibre intake, as well as the processing of the food.
  • When you reduce calorie intake, technically you reduce the thermic effect a bit as well.
  • In other cases, it plays a role when people change their intake. For example, if you switched from a minimally processed diet to a highly processed diet, calories burned through this well decrease a bit.
  • Arguably this one is the least relevant. But it is a great example of how our intake affects our expenditure.

Increase in Hunger and Cravings

  • When you are consistently in a calorie deficit, it is common for hunger and desire to eat to increase.

*insert diet break chart*

  • In some cases, people find it a lot easier to stick to a decent size calorie deficit initially. 
  • If there is not some form of structure that ensures intake remains the same, in many cases (not all) people will unintentionally increase their intake as the weeks go on. 
  • This obviously can reduce the size of the deficit, or erase it entirely.

Inconsistency or Unintentional Routine Changes

From the mental perspective, it is common for people to be more rigid with their actions earlier on with a deficit. Sometimes people are really consistent initially. And then they might still be quite consistent after that, but there could be a small gap. This could be with either exercise or nutrition. 

This obviously can contribute to reducing the size of the deficit as well.

Summary

One of the trickiest things is that there is rarely one explanation. Often it is a combination of factors. 

If this is relevant for you though, you have 3 options:

– Reduce calorie intake further (either through consistency or changing the plan)

– Increase calorie expenditure (either through incidental movement or formal exercise)

– Take the emphasis off fat loss for a bit.

It comes down to a case-by-case basis which one makes sense for you. But if you are at a plateau for a while, it makes sense to make a change. 

Relevant Blogs / Resources

Relevant Blog Posts:

Relevant Podcasts:

Relevant Studies: