Whatever doesn’t fill you, makes you...hungrier?

19 days in! I'm feeling good. Not great, but good. Sleep is definitely not my friend at the moment, and I’m not sure what that’s about- maybe a withdrawal side effect, maybe nothing to do with this sugar-free life. On the craving side, not much to report, which is a plus (although as I typed that, I suddenly really wanted licorice, really badly, damn).

Here’s another plus: I’ve definitely felt fuller lately, even though I'm eating less. Strange, but true. Of course I’ve changed quite a few things about my diet. I’ve cut almost everything sweet out (except fruit and veg of course) because if it’s sweet, it’s most likely sugared. I’ve also added fat back into my diet: no more ‘low fat’ versions for me. And along the way I’ve also probably added more fibre as well through fruit and veg and other healthy stuff.

I wanted to look at the whole fullness thing in more detail because I don’t really understand it. Why do different foods make us feel ‘full’?  Is there a magic combination of foods which will help me to feel not just full of food but satisfied and not looking around for more? Or do I just need more self-control to stop me licking the plate clean and then helping myself to the post-dinner TimTam?

There are two parts to determining how much we eat at a meal. If something is delicious, we eat more of it. (mmmm licorice...stop that). So our perception of food and the positive feedback we get from eating is really important. We also get feedback from our bodies, telling us when to stop. As these guys point out, to reduce your energy intake you either have to decrease the ‘morishness’ of your food, or increase the feedback from the body (or your response to that feedback) that stops you eating.

Eating boring food might be a great way of reducing your meal size and (in the long term) your weight, but try serving your family a couple of boiled parsnips for dinner tomorrow and see what they think about this idea (feedback can be posted below!) Perhaps our tastebuds are spoiled brats with all the food choices that we have, perhaps we just have too much (inborn? socially developed?) expectation that food should taste good, not bad. Either way, I’m not convinced that it’s plausible long term to work on energy intake by eating only unappealing food.

Nope, it’s going to have to be up to the body on this one- so, what can you do for me, digestive system? Turns out it can do quite a lot, but in the interest of keeping this post readably short, here is the cutback version of some processes which are far, far too complex for me to understand with just some light reading in my spare time. But, keeping to the shallows, I’ve gathered a few interesting facts for your edification.

The most obvious signal to stop eating is the physical feeling of fullness in your stomach as it fills up with all that yummy food. If you get through the entree and main and feel like you are bursting, this is your stomach trying to say ‘hey, don’t get dessert on my account, I’m done here’. Fibre is great at filling the stomach, but fat and protein also play a role. (I’ve learned some great things about fibre while researching this, but I’ll save that for another day. Bet you can’t wait!). The body doesn’t just rely on the ‘full’ feeling to make you stop. A hormone called Cholecystokinin (which is also helpfully called CCK, a far easier-to-type name) is stimulated in the small intestine, particularly if you eat a lot of fat and protein. CCK helpfully sends a signal to the brain to say ‘enough already’, just a brief message to get us to stop for this particular meal. We have the ability to ignore or overcome this signal and keep eating, and we regularly do. It’s a handbrake rather than a tire clamp. Stimulating CCK during one meal has little effect on what you eat for the rest of the day (as I read here), but may make us more sensitive to the full feeling in future meals. There is an article specifically about this hormone here if you are interested.

Another important hormone in helping us put the fork down is leptin. Leptin is made primarily in your fat stores, and the greater your love handles, the more leptin is whirling around the body, which should mean that you eat less. Leptin seems to be the body’s way of keeping tabs on your nutritional status. It sends ongoing messages to the brain saying ‘hey there, no need for big, high energy meals right now, there’s plenty of fat to get us through winter’ (I’m paraphrasing, of course). If there’s a lot of leptin, it also increases the amount of energy you burn. What a gem- I love this little guy!

The catch is that it seems we can become resistant to the effect of leptin. In fact, to quote these researchers, “Most forms of obesity are associated with diminished responsiveness to the appetite-suppressing effects of leptin”.  You knew I couldn’t go a whole post without mentioning fructose- my sweet nemesis- so here it is. When fructose is processed by the liver, the liver produces triglycerides. These fatty little fiends have been shown to block the uptake of leptin in the brain, meaning that while the leptin is talking, the brain isn’t listening.  These researchers showed that this leptin resistance can develop without any outward sign (such as weight gain)- until we also start eating high calorie meals- then BAM! we gain serious weight because leptin is not able to tell the brain what is going on. If this is true, then eating high calorie food in conjunction with fructose is a recipe for obesity. And fructose is terribly easy to eat.

I'll just mention as well that there seem to be important links between leptin and CCK, including evidence that if either hormone is reduced or blocked, then the other doesn't work as well as it should.

So there you have it, a whistlestop tour of how your body wants to help you [insert pic of Uncle Sam in your imagination]. There are a bunch of processes, hormones and signals that we as choice-wielding humans can listen to or ignore, and a bunch of foods which can turn the volume up or down. And if this all feels too complex, there is always the boiled parsnip option :)