T Nation

Do Our Bodies Adjust To Bodyfat %

#1

I have a friend who went from:

8% - 13% over a couple of months
13% - 8% in about 6 weeks.

However his natural bf% (no specific diet or training regime) was 8% from his teenage years until he pigged out.

At 13% he was a slob, ate fast food multiple times a day, didn't exercise, drank 400ml vodka and a litre of beer two nights a week.

He dropped the weight lifting+cardio+clean eating (not counting cals or anything)

Now he has dropped his diet except for eating enough protein, eats fast food and drinks the same alcohol but he has kept his gym routine and managed to maintain the lean 8% (still has very visible 6 pack).

What I am asking is, do our bodies adjust to a bf% once we get there or are they trying to bounce back to our natural bf% state ?

I able to get away with anything he does at my 14% vs his 8% although I carry much more muscle.

At 14% I can eat kfc, pizza, chinese food etc as long as I get enough protein I don't get fat gain weight, That was my diet plan for 9 months, just get enough protein through whey and have 1-2 large 1500 cal meals and I gained a bunch of muscle and no fat.

If I drop to 8% will I be able to live the same way, or is my body cursed to bounce back to 14%. But my friend can get away with slacking since he is naturally 8-10% since his early teens ?

#2

Depends on metabolism really. Everyones bodies are different in what they can handle, how they process nutrients and how fast.

#3

While there are plenty of factors that come into play (most notably, the uniqueness of different people), it’s been discussed before how leaner people tend to have better insulin sensitivity. When you add in the fact that in getting lean (like your friend), they probably added lbm, which contributes to RMR each day (as well as the constant training and the cals it expends!)

I know that when I was off-season, I would do similarly; making sure I got enough protein and healthy fats, but then also going a bit outside of what people might consider strict, or “clean” (damn I hate that term) eating. After having dieted down for a contest, each successive year I found that I could handle a greater amount of carbohydrates without really getting fat.

But again, as ELS pointed out, veryone is different, and even then, your body isn’t in a static situation.

S

#4

A proposed mechanism would be the Leptin excretion from fat cells and the sensitivity of the body to it.

The fuller the fat cells, the more Leptin they produce and since Leptin makes you feel full and increases metabolism, you get that nice warm feeling after a good meal. But if your fat cells get fuller and fuller and then stay full for a longer period of time, they always excrete higher amounts of Leptin, leading to desensitation to Leptin in the brain and other tissues.

So you need more Leptin to get the same feeling of satiety and the fat cycle continues. If you drop weight then, your brain gets far less Leptin than before which makes getting “full” much harder and you tend to eat more, which would result in the typical jojo effect. But the brain adopts after some time at low bodyfat and gets resensitized to a Leptin, so after being lean for some time, it gets easier and easier to stay lean.

But Leptin has also an effect on metabolism and after dieting down, the metabolism gets weaker (it will recover with resensitization) but a big fat meal will not be burned of that easily as with the “usual” Leptin level and therefore will rather be stored as fat. Being lean for a longer time will mean the effect of Leptin on metabolism will recover and even though your pal eats a lot of crap, most of it will get burned instead of stored.

As for being lean in the “teenage years”, maybe the Leptin resensitization happens faster if the brain is used to a lower leptin baseline (probably).