Thanks for your comment! There are undoubtedly people who eat like pigs, never exercise, and are still skinny. However, truth is, many factors can affect their energy balance. For example, the nutritional profile of their diets (are they eating high-protein diets, which have a higher thermic effect of food, thus, causing them to burn more calories? What about their fiber content?) and how physically active they are.
While they don’t exercise, they may be expending energy in other ways (non-exercise activity thermogenesis). Do they work an active job? Do they fidget a lot? We don’t know the specific amount of calories they’re eating versus the amount they’re burning.
But given that research consistently shows that a calorie deficit leads to weight loss and that a calorie surplus leads to weight gain, I’d say that they’re eating at their maintenance calories–even if it appears hard to believe.
Also, you’re right that people do lose weight on ketogenic diets. But that’s really because the ketogenic diet has appetite-blunting effects:
- Ketone bodies appear to curb appetite
- Increased protein intake is often a result of following the ketogenic diet. Because protein is a highly-satiating macronutrient, eating more protein alone can curb appetite.
And these, when added together, means a lower calorie intake–helping keto dieters stick to a calorie deficit (even if they don’t realize it).
Ultimately, people losing weight on the ketogenic diet doesn’t disprove CICO. Instead, you can think of the ketogenic diet as a tool that helps individuals better stick to a calorie deficit.
I hope this was helpful, Dean!