So we all know the media focuses way too much on “fat=bad”, but not everyone is aware of why this is wrong besides putting forth unnecessary pressure for the world to shuck any and all fat they may possess. At this point, if you’ve read my last post, you know why we need fat. But I know what you’re thinking, “Ophid, too much fat is bad for you! Also your room is a mess.” Right on both counts, sort of. That “too much” is hella vague and I can find everything in my room that I need to find, thank you very much. Anyway, “too much” fat is highly dependent on an individual’s body chemistry. So you can have two people of greatly differing sizes, that will never share a jean size in their lives, but they’ll share excellent health and blood work worthy of a gilded frame over the mantle. Of course, the key is that they both maintain healthy lifestyles, doesn’t matter what your metabolism, if you live on Red Vines and French fries you better just sit back and watch your blood pressure rocket to the moon. Lot of models out there have skinny, tiny bodies and skinny, tiny blood vessels from all the cholesterol they’ve accumulated. So they may be walking the runway, but really, it’s what’s on the inside that counts.
Back to the body chemistry. Another vague phrase, but it won’t stay that way, I promise. First, understand that cells in adipose tissue releases a chemical called leptin. Leptin signals satiety, and the more fat cells present, the more leptin is released. As a result, overall appetite decreases. Conversely, the less stored fat, the greater the appetite. Which explains why I never stop eating. I’m like a hobbit, except hobbits don’t turn feral when hungry. So there’s that.
Feral rage brings me to my next point; adipose set points. Although the general rule is more fat leads to more leptin secretion, bodily reaction to leptin levels in the blood vary greatly. Example: anyone here read the Oz books? There’s a character called the Hungry Tiger who, I kid you not, is always talking about wanting to eat fat babies. The Hungry Tiger wants to eat all the time but does not eat as much as he wants because he’s afraid he’ll eat a baby, or something. I have a deep kinship with the Hungry Tiger. Except for the baby thing. Anyway! If the Hungry Tiger actually got to pig out on some baby-free food and gained wait, the rise in leptin would make his appetite drop dramatically. He would be The Tiger Formerly Known as the Hungry Tiger. Actual tigers are like this; they’re adapted to a food-plentiful environment and though they do sit around a lot, when they do gain some weight, their appetite disappears. As a result, they remain lean and agile. Conversely, a high adipose set point means that it takes a lot of stored fat and high leptin secretion before appetite decreases. This set point is perfectly adapted for “feast or famine” habitats; animals will bulk up until their body hits a good stopping point and then they’re good to go. These set points keep individuals at very stable weight ranges. So if you’re someone watches their diet like a hawk (whatever your size), you’re eating right, eating enough, but budge nary a pound off the norm, it’s because your body is adapted to a very specific lifestyle and won’t budge for love or money.
Besides an unhealthy diet, problems arise if you eat beyond satiety, or have a genetic mutation. Specifically in the ob gene, the ob gene controls leptin release, if that mutates it becomes functionally absent (it doesn’t work) so leptin is not produced. As a result, chemical satiety signals disappear almost completely. This is a heritable trait and means you have a very variable weight but tend towards heaviness to the point of obesity.
Hope this gives y’all a better understanding of energy, body fat and body type adaptations. If you’ll excuse me, I’m going to go clean my room…
He’s totally gonna eat that kid.
Source
Sherwood, Lauralee, Hillar Klandorf and Paul Yancey. 2005. Animal Physiology: From Genes to Organisms. Thomson Brookes/Cole, Belmont, CA.
Daily Science (blog) 