Tuesday, July 28, 2015

Point Density

For me, doing weight watcher's well is pretty much impossible without doing a fair amount of tracking. Given that, any system that makes tracking easier — or that makes faking it easier when meticulous tracking is untenable — is a huge boon. Learning to weigh my food and think in terms of point densities has been just such a system.

A lot of people seem to think weighing your food is a lot of work, but it doesn't have to be. Putting a scale under your plate doesn't get any extra dishes dirty and it doesn't require any extra steps (you were already going to serve yourself, right?). As I'll explain below, for most foods that "count" towards your PPV target for the day, simply weighing the food in ounces would be a pretty good estimate for how many points you're eating. So if you're going to get lazy about tracking, you could do worse than to weigh all the non-veggies on your plate and keep track of that number.

I got to this lazy method of tracking after months of carefully tracking every item I ate. I was already enough of a geek chef to know that measuring weight is superior to measuring volume, so it didn't take me long to start weighing all of my food.

There's a thing that happens when you weigh ingredients as a cook where you realize that the density of nearly all food is 1 (that's because so much food is actually made of water). Well, it turns out that a similar rule applies to weighing food for Weight Watchers: the PPV-density of an enormous number of foods (specifically: foods with a heft to them similar to that of water) is also 1:

FoodPoint Density (value of 1 oz)
Most Fruits & Vegetables0
Potato, baked1 (0.67)
Egg1 (1.03)
Cooked pasta1 (0.99)
Rice (brown or white)1 (0.79,0.83)
Hamachi (raw yellowtail)1 (0.97)
Chicken breast - meat only1 (1.05)
Pork chop, cooked lean1 (1.15)
Swordfish1 (1.17)
Salmon1 (1.45)
Cooked pasta1 (0.99)
Bread2 (1.68)
Chicken thigh - meat only2 (1.65)
Pork Ribs, country style2 (1.98)
Pork Sausage2 (2.48)
Cheese3 (3.04)
Bacon, cooked crisp3 (3.41)
Butter6 (5.83)
These are approximations, but not by all that much in many cases. For the amounts we eat, the difference between the estimates shown here and the actual number (in parentheses) is likely to amount to a single PPV, if it amounts to anything at all: at any rate, since the errors don't consistently work in any given direction, it's likely to be a wash.(1)

And the real advantage is that I've actually learned to think of food densities in a much simpler way, like this:
Fruits and vegetables0
Cooked starches/grains & lean protein1
Fatty meat2
Cheese & Really fatty meat3
Butter & oil(2)6
If you eat mostly real, non-processed food(3), this cheat sheet + a scale will let you pretty much tally up your foods all simply by placing a scale under your plate and hitting tare each time you add something in a different point density category. Since much of what you eat belongs in the density 1 column anyway, you might not even have to hit tare between items: just weigh your lean proteins and grains and the number on the scale (in ounces) is a pretty good approximation of the number of points. Done.

This also helps with unfamiliar foods. Cooking polenta? You're probably safe approximating a density of 1. Tortilla? It's about as moist as bread, so let's assume a density of 2. Reheating left over mac&cheese from Panera? You could do worse than to assume a PPV-density of 2 (right between cheese & noodles) though it's likely not actually as bad as ½ cheese ½ noodles. (4)

I should point out that one consequence of this is that many of the differences between healthy and less healthy food start to evaporate: brown rice vs. regular rice, pasta vs. lean protein — on this chart, they don't seem to make any difference.

That said, I think a little time experimenting with tracking your food will tell you how a meal affects you in terms of satiety. All points are not equal, and we all know that if you eat foods that don't fill you up, you will find a way to eat later to make up for the difference, and often not a good way.
Also, lest you think that the points system is not likely to lead to healthy choices, it's worth remembering the enormous incentive WW provides to eat 0-points food. If you're trying to fill a plate, its clear that any way you slice it, tracking points is going to incentivize you to fill up with fruits & veggies.


1. Imagine, for example, a dinner plate with a 5 oz. serving of pork chops, a 6 oz. serving of brown rice, and some steamed vegetables with a tablespoon of butter (1/2 ounce). The quick estimate says this is a 14 point meal. If we go back and calculate it more carefully, we get 4.74 points for the brown rice, 5.75 points for the pork, and 2.92 for the butter, for a total of 13.415 points, which WW would round up to 14 anyway — same difference. The point is, even with some of our foods that seem like the "1" estimate is more inaccurate, it tends to not matter overall when you add up the overall points.
2. Note that most oils have a density higher than 6 since, unlike butter, they don't have any milk solids or proteins getting in the way of the fat. That said, oil is one of the few ingredients I actually typically measure by volume instead of by weight since I'm often adding it either to a pan or to a salad (which I don't weigh since it's all value 0). Given that, the fact that oil is significantly lighter than water means that the 6 approximation is much more accurate for a fluid ounce than for a regular old ounce.
3. As you can probably guess, many processed foods break both the rule of thumb that the actual density of foods is 1 and my WW corollary that the PPV-density of most foods is 1PPV/ounce. I eat few enough processed foods that I tend to learn the servings and weigh them that way -- when I eat cereal I weigh it in grams, for example. Nonetheless, here's a quick table of PPV estimates for common processed ingredients:
FoodPoint Density (value of 1 oz)
Popcorn, light3 (2.85)
Multigrain Cheerios3 (2.71)
Corn Flakes3 (2.79)
Frosted Flakes3 (2.81)
Saltine Crackers3 (3.08)
Animal crackers3 (3.40)
Tortilla Chips4 (3.62)
Cheetos Puffs4 (4.11)
Potato Chips4 (4.24)
Milano cookies4 (4.39)
Edy's Slow Churned Caramel Ice Cream1 (1.32)
Premium Ice Cream2 (2.06)
Pound cake3 (3.12)
It seems like we could simplify this to something like this:
FoodPoint Density (value of 1 oz)
Dry snack foods3
Dry greasy or sugary snack foods4
Bready stuff2
Cakey stuff3
4. Actual PPV values: Polenta: 1 (0.66), Tortilla: 2 (2.22), Panera Mac & Cheese 1 (1.13). The Panera number is pretty low, so I'm a bit skeptical: it looks like what might be going on is that Panera Mac & Cheese is actually super-dense: I'll note that WW puts a cup at 10 points and 246 grams -- with a real density higher than water (1.08). I'll be honest and say I've always estimated prepared mac&cheese at 1.5 or 2 depending on how generous I'm being with myself on a given day. A quick check of the WW database shows that for Papa Gino's Mac & Cheese, 2 is the more accurate estimate (1.58 to be precise).

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