Between packed work schedules, personal obligations, and the general “hustle culture” of today’s society, it’s safe to say that we all appreciate convenience where we can get it. Luckily, in the world of nutrition, convenience is becoming much more common. We now have access to health food delivery services, pre-portioned meal kits, and even modernized frozen dinners made with wholesome ingredients; but did you know that there are also drinkable meals out there? That’s right, we’ve taken convenience to a whole new level. So, how are we to know which of these options are good for us? More specifically, can we really drink our dinner from a bottle? Read on to find out what the research says about this wave of nutrition convenience.
What are the options?
Depending on your age, you may remember when the only liquid meal option out there was SlimFast. However, things are definitely different now! Since this trend has had a resurgence and grown more popular, tons of other options have emerged. Many protein powders, such as Orgain, Optimum Nutrition, Shakeology, Nuzest, and Vega, are utilized as meal replacements because of – you guessed it – their high protein content (usually 20-30 grams per serving, which may be an appropriate amount of protein for someone to take in at a meal, depending on nutritional needs and other factors) (1-5). However, given the low calorie level of most protein powders (many offer as little as 110-150 calories per serving), it can be difficult to meet your nutritional needs with protein powder alone, even if it’s mixed with a calorie-containing beverage like milk. However, there are also options providing more calories and are marketed as true meal replacements, like Soylent, OWYN, Ample, and Huel. These options are similar to the protein powders in that they boast a high protein content, but they’re different in that they are often sold as readymade drinks and tend to have around 400 calories per serving, which is a bit closer to the number of calories that some people will take in at a meal (again, this level will vary) (6-9).
So, what’s the verdict?
As is common in the world of nutrition, the answer to the question “Can we drink our dinner from a bottle?” is really… it depends. Many meal replacement drinks available today are nutrient-dense, provide adequate kilocalories, protein, and fat, and have minimal additives. Depending on your individual situation, there may certainly be a time and place for these products to fit into your life. Having said that, it is also important to understand the importance of chewing in our lives, which we can only fully get from actual food. That’s right, chewing! Research shows that diet-induced thermogenesis, known colloquially as “calorie burn” or “revving up the metabolism,” is decreased when we consume liquid meal replacements instead of consuming meals – and it’s even further decreased when we consume those liquid meal replacements quickly, without taking the time to taste them (10).
As a portion of total daily energy expenditure (with the other portions being resting energy expenditure and physical activity), diet-induced thermogenesis describes the increase in energy expenditure that occurs in order for our bodies to be able to absorb, transport, metabolize, and store the food we consume (10). Some studies have shown that this increase in energy expenditure, though modest when compared with our Resting Energy Expenditure (REE) or physical activity, can have a significant effect on our ability to maintain our body weight (10, 11). This research aligns with themes that have emerged from other studies, including a 2015 systematic review and meta-analysis that underscored the ideas that masticating, or chewing, clearly assists in the processes of digestion and optimal nutrient absorption, as well as that chewing is important in regulation of appetite and food intake (12). It turns out that chewing may even have an effect on cognitive performance – how’s that for a big impact from an everyday action? (13)
What about smoothies?
Smoothies are an interesting topic, as they are a bit of a hybrid between regular “chewable” meals and liquid meals. They are drinkable, but they are usually significantly thicker than a liquid meal. As previously mentioned, it is well understood that chewing has an impact on our appetite and on how we regulate our food intake, but why is that? (12) In short, digestion begins in the mouth, and when we chew, we start to release important enzymes that assist in the digestive process; if we consume a liquid that does not require any chewing, the satiating power of our calorie intake decreases (14). With that in mind, it begs the question: have you ever thought to chew your smoothie?
Research tells us that a smoothie will still have less satiating power than a fully chewable food item or meal, but if we can aim to engage in the act of chewing when consuming a smoothie, we may be able to initiate our digestive process in the mouth as intended, at least more so than when consuming a liquid meal (15). Overall, smoothies are certainly more “food-like” than liquid meals, so it follows that their satiating power is greater than liquid meals (15). If you don’t have time for a full meal, but have a blender on hand, try a smoothie! For optimal calorie- and nutrient-density, staying power, and blood sugar stability, aim for a source of carbohydrate, protein, fat, and fiber when blending up one of these delicious icy beverages.
Got questions, or interested in learning more about your options to achieve optimal satiety and satisfaction from meals and snacks? Our dietitians at INC Nutrition are here to help. Reach out today!
Hamada, Y., Hayashi, N. Chewing increases postprandial diet-induced thermogenesis. Sci Rep 11, 23714 (2021). https://doi.org/10.1038/s41598-021-03109-x
Ho KKY. Diet-induced thermogenesis: fake friend or foe? Journal of Endocrinology. 2018;238(3):R185-R191. doi:10.1530/joe-18-0240
Miquel-Kergoat S, Azais-Braesco V, Burton-Freeman B, Hetherington MM. Effects of chewing on appetite, food intake and gut hormones: A systematic review and meta-analysis. Physiol Behav. 2015;151:88-96. doi:10.1016/j.physbeh.2015.07.017
Hirano Y, Onozuka M. Chewing and attention: a positive effect on sustained attention. Biomed Res Int. 2015;2015:367026. doi:10.1155/2015/367026
de Graaf C. Why liquid energy results in overconsumption. Proc Nutr Soc. 2011;70(2):162-170. doi:10.1017/S0029665111000012
Rogers PJ, Shahrokni R. A Comparison of the Satiety Effects of a Fruit Smoothie, Its Fresh Fruit Equivalent and Other Drinks. Nutrients. 2018;10(4):431. Published 2018 Mar 30. doi:10.3390/nu10040431