Also an interesting take. I submitted this question to the Podcast, I’ll be interested to see whether Coach Chad weighs (no pun intended) in on it.
That’s not how physics works.
F=MA is the calculation used to determine force being applied to something. In this case, the mass is the total moving mass of the bike + rider. The A is how fast the bike and rider accelerate.
I can see how by looking at the equation, keeping all things the same , one might assume that means a heavier rider = more force. But it doesnt. As weight drops, the acceleration of the system increases. You just go faster quicker. Force stays the same.
The one area your view does hold true is for falling objects (or riding downhill). All mass accelerates towards the earth at 9.8m/sec squared. Double the mass, double the force against the object resisting that acceleration, be it wind resistance, or a bathroom scale.
Also, this is easily testable. Go fill a backpack up with bricks and see if you go any faster.
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My understanding is that weight of the leg is not providing the force to drive pedals in a circular motion. Indeed if I’m at a standstill the weight of my leg will not push me forward. And if I’m coasting the weight of my legs will not continue to drive the pedals.
Instead, muscle contractions are providing the force. And those muscle contractions are powered by a combination of:
- aerobic energy production, which depends on slow-twitch muscle fibers
- anaerobic energy production, which depends on fast-twitch muscle fibers
All things being equal - same weight, same aerobic capacity, same % slow-vs-fast twitch fibers, same metabolic efficiency - if you have larger leg muscles then a friend then you have more muscle fibers to provide more energy.
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I’m confused by this - why would this theoretical person lose any power capabilities? The fat does not help in force generation.
If you just magic away 10 lbs of fat with no impact on anything else your ability to generate power should not have changed at all
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exactly.
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All good points, and I’ve reconsidered my position. Certainly truncal obesity has no bearing. I was thinking about fat legs pushing down on pedals. Gravity assists with the push. But on the back end of the pedal stroke, any gain would be negated. So i retract my initial statement.
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I love it. This was such an interesting discussion.
Sounds like the final takeaway is: Train intelligently, be mindful about maintaining muscle (not underfueling), and staying around ~315 FTP while losing weight should definitely be possible, just a question of how slowly the weight drops. 
For now I’m set on: Mid-volume with an extra Pettit on Friday, drink Cytomax on the bike, drink whey protein after, add some weightlifting back in, and slash and burn all junk food of every kind …
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Initial target should be around 250-500 calorie deficit per day, and watch your macros. You want to avoid being in a situation where your body uses lean muscle as fuel. Counting calories and estimating daily calorie burn isn’t an exact science, so keep track and adjust as needed. I’ve always been conservative and look to lose 0.5-1.0 pounds a week.
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