In this LAB note
Question · Hypothesis · Method · Results · What Failed · What We Learned · What Changed at MOMS
Question
When a MOMS shake splits its liquid between two ingredients instead of one, what changes besides the liquid volume?
Hypothesis
We expected a second liquid to add volume without adding calories, because every recipe is built to a calorie band. If so, the extra volume has to come at the expense of solid ingredients, and the shake’s energy density (calories per gram of everything in the cup) should fall. That expectation comes from Bell and colleagues (1998), who found that people ate a similar weight of food whatever its energy density, so lower-energy-density food meant fewer calories eaten. We did not expect the pattern to be clean.
Method
Published research: Bell, Castellanos, Pelkman, Thorwart and Rolls (1998) gave 18 normal-weight women low-, medium- or high-energy-density entrées for two days at a time. Intake by weight was similar across conditions, so energy intake followed energy density: 1,376 kcal on the low-density condition versus 1,800 kcal on the high-density one. That was a study of entrées in women, not of blended shakes, so we use it only to say why energy density is worth measuring. Internal analysis: we split all 201 recipes in our formulation database by whether the Liquid field names one liquid (164 recipes) or two (37). For each recipe we summed liquid millilitres, summed the grams of every other ingredient slot, and divided the recipe’s calories by that combined weight to get calories per gram. Treating 1 ml as 1 g is an approximation, and these are formula weights, not a measured cup.
Results
Two-liquid recipes average 279 ml of liquid against 218 ml for one-liquid recipes (medians 300 ml and 195 ml). They average 339 g of solid ingredients against 371 g. Calories are 375.5 against 374.9, a 0.6 kcal difference, and protein is 32.6 g against 33.1 g. Total formula weight is 618 g against 589 g, so the second liquid adds 29 g of net weight, not 61. Calories per gram average 0.62 for two-liquid recipes and 0.67 for one-liquid recipes, about 7% lower; 26 of the 37 two-liquid recipes fall below the one-liquid average. EY-W1-ENERGY-002-V1 shows the pattern: Coconut Milk 195 ml plus Soy Milk 150 ml, 294 g of solid ingredients, 386.7 kcal, 31.9 g protein. WAY-W2-COOL-002-V1 goes further: Soy Milk 150 ml plus Coconut Water 300 ml is 450 ml of liquid, only 259 g of solids, and 391.6 kcal with 32.3 g protein.
What Failed
The simple story does not hold on its own. EY-W1-ENERGY-006-V1 uses a single Soy Milk 300 ml, 328 g of solids, 345.2 kcal and 31 g protein, which works out to about 0.55 kcal per gram, lower than the two-liquid EY-W1-ENERGY-002-V1 at about 0.61. And 11 of the 37 two-liquid recipes are not below the one-liquid average at all. A volume-matched control also cuts against us. The 64 one-liquid recipes with at least 250 ml of liquid average 295 ml, 377 g of solids and 359.7 kcal, which is 16 kcal fewer than the two-liquid average. So it is not liquid volume that holds calories flat; two-liquid recipes simply were not built lighter than comparable one-liquid ones. Our Score runs slightly higher for two-liquid recipes (15.4 versus 14.9), but Score does not measure energy density, so we draw no causal link. We also measured nothing about fullness, and these recipes were designed, not randomly assigned.
What We Learned
The number of liquids in a recipe tells you almost nothing about its calories. What it does tell you is how the cup’s weight is divided: our two-liquid recipes hold more pourable volume and less solid food at the same calorie level, which lowers calories per gram by roughly 7% on average, with exceptions. Whether that makes a shake feel more filling is untested here. The published evidence is from whole meals, so we treat energy density as a number worth watching, not a promise.
What Changed at MOMS
When a draft recipe feels thin on volume, we will now try splitting the liquid before adding more solid ingredients, and compare the two versions at the same calories. We are also adding calories per gram of total formula weight to the formulation sheet next to kcal, so we can see which recipes sit well above or below the average before we describe them as light or filling.
References
Bell EA, Castellanos VH, Pelkman CL, Thorwart ML, Rolls BJ. Energy density of foods affects energy intake in normal-weight women. Am J Clin Nutr. 1998;67(3):412-420.
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