In this LAB note
Question · Hypothesis · Method · Results · What Failed · What We Learned · What Changed at MOMS
Question
What combination of macronutrients makes a whole-food shake feel genuinely filling, not just high in protein, but actually satisfying for hours afterward?
Hypothesis
We expected protein to be the dominant driver of satiety, and hypothesized that a high-protein, low-fat shake would outperform other formulas on hunger ratings.
Method
We drew on three lines of published research. First, a randomized clinical trial using whole avocado, a natural fat-fiber combination, in place of carbohydrate energy at breakfast in overweight and obese adults, which measured satiety alongside gut hormones PYY, GLP-1, and insulin over a 6-hour crossover window. Second, a 2013 study in Obesity showing that high-protein breakfasts produced significantly larger increases in PYY and GLP-1, the body's own satiety-signaling hormones, compared to high-carbohydrate breakfasts. Third, a comparative study of high-carbohydrate, high-fat, and high-protein meals in Chinese men, which found that a high-carbohydrate meal blunted postprandial ghrelin, PYY, and GLP-1 responses relative to fat or protein meals. Internally, we ran a 28-person panel testing three shake formulas at matched calories: low-fat/high-carb, a moderate blend, and a higher-fat/higher-fiber formula, tracking hunger ratings on a standard scale at 1, 2, and 4 hours after drinking.
Results
The published literature converged on a consistent theme: fat and protein each independently stimulate PYY and GLP-1 more effectively than carbohydrate does, and the avocado trial specifically showed that a fat-fiber combination significantly suppressed hunger and increased PYY/GLP-1 relative to a carbohydrate-matched control, with lower insulin response as well. Our internal panel found the same pattern behaviorally: the higher-fat/higher-fiber shake produced hunger ratings 1.5-2.3 points lower on our scale than the low-fat/high-carb shake at every time point we measured. We also tested a "protein-maximized" formula, 40g+ protein, under 5g fat, expecting it to be the most filling option. It performed no better than the low-fat control.
What Failed
The protein-maximized, near-fat-free shake was our most counterintuitive result. Despite having the highest protein content of any formula we tested, it did not outperform the low-fat/high-carb control on hunger ratings at any time point. Protein alone, without fat or fiber alongside it, didn't translate into the "holds you over" feeling we expected.
What We Learned
Satiety looks like a three-way negotiation between protein, fiber, and fat rather than something protein delivers on its own. Fat specifically appears to play a real, hormone-mediated role, not just a "makes it taste richer" role, in how full and satisfied a shake makes someone feel.
What Changed at MOMS
Our internal fullness-scoring model for recipes now weights fat and fiber alongside protein rather than treating protein as the only lever for satiety. Several recipes' fat content increased as a direct result of this testing.
References
1. Using the Avocado to Test the Satiety Effects of a Fat-Fiber Combination in Place of Carbohydrate Energy in a Breakfast Meal in Overweight and Obese Men and Women: A Randomized Clinical Trial. Nutrients, 2019. https://doi.org/10.3390/nu11050952 2. van der Klaauw AA, et al. High protein intake stimulates postprandial GLP1 and PYY release. Obesity, 2013;21(8):1602-1607.
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