Scientists haven’t fully grasped how our diet evolved nor what exactly transpires in our bodies as we munch on burgers or pick through salads. But research has demonstrated that the diversity within one’s meals, including aspects like texture and taste, matters for our health. Experiments have demonstrated that we tire of specific foods and tend to move on to new ones shortly after — consider why you may have room for dessert after a heaping savory meal. Humans may have developed this behavior to ensure proper nutrient intake. 

Researchers have observed this phenomenon, known as sensory-specific satiety, among animals and children (who haven’t exactly memorized the food pyramid).

Choosing to turn entirely to liquid meals when it isn’t otherwise necessary means overriding our hard-wired instincts. While meal replacement drinks may come in an increasing variety of flavours, you may encounter a relatively similar consistency and miss out on the crunch and flavours from a wider range of foods.

Eliminating that fundamental variety-seeking that we have is not a good thing.

It has been found that liquids don’t make us feel as satisfied as solids do. One possible explanation: “complex” liquids like smoothies and protein shakes leave the stomach within 40 to 60 minutes — literal “fast food,”  while protein- and fat-rich solid meals can linger twice as long. 

Exclusively slurping on SlimFast or Soylent also means that you’ll miss out on the joy of chewing. As it turns out, chewing is rewarding even when food is absent — consider why some people tear through packs of gum. Most importantly, munching signals the body to prepare for digestion, and longer chewing might even help us eat less.

Beyond feeling bored and perhaps hungry and disgruntled, what health effects come with exclusively drinking your meals? While weight-loss trials have deemed months-long liquid meal replacement plans as generally safe under medical supervision, there isn’t much data on the safety of a regimen filled with newer drinks like Soylent and Huel (apart from small trials carried out by the companies themselves).

When drinking supplements, it may be difficult to get enough fiber, which helps regulate hunger and blood sugar levels. Brands vary in their fiber content. The powders from Huel and Soylent offer a considerable amount per serving, while Boost and Ensure drinks offer little to none. Meanwhile, drinks in the latter category can contain extremely high amounts of sugar, which add up if you’re throwing back multiple per day. Drinking your food can also affect drug absorption, since thick liquids may delay the dissolution of drugs.

Liquid diets are also ironically associated with dehydration, likely because people forget to drink enough water and aren’t getting much from food (which provides around 20 to 30 percent of the H2O we need)

As much progress as nutrition has made, we don’t understand all the complexities of what’s in different foods. And although some brands claim to stuff all of the necessary nutritional components into a bottle or powder, this feat may not actually be possible. We haven’t necessarily pinpointed all of the compounds that make certain foods healthy, and how they might work together to produce specific effects.

Fruits and vegetables, for example, have all kinds of phytonutrients that aren’t necessarily even defined yet.