Most advertisements for meal replacement shakes show a toned athlete taking a sip, making us believe that if we drink their product we’ll look like that, too.

They’re marketed as healthy and convenient replacements to solid food.

But are meal replacement shakes as health-promoting as they seem?

Shona Wilkinson, lead nutritionist at Dr. Vegan, told HuffPost that while they do have some benefits, the cons may outweigh the pros.

“As idealistic as it may sound, meal replacements should not be relied upon as an alternative to food, especially in the long term. Many nutrients in food are not classified as ‘vitamins’ or ‘minerals’, and therefore not included in meal replacements,” Wilkinson said.

When food is taken in powdered form as opposed to its natural state, a lot of valuable nutritional compounds are lost, she said.

Whether adding powder to milk or water, liquid meals should be taken as a temporary substitute to whole foods to ensure daily calorie and nutrition, according to nutrition experts.

Registered dietician Amy K. Fischer told The List, “Food first is always the best policy. ... I would not recommend drinking more than one a day except if there is an underlying reason, like a medical prescription.”

Meal replacement shakes are not a long-term solution to weight loss. They do not promote lasting health benefits like creating a healthy diet with solid food would.

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A study published in the National Institute of Health found that liquid meals are less satisfying and do not curve an individual’s appetite as fully as a solid meal would.

Chewing your food is important. Wilkinson said that if you have gut health issues, it is advised to not drink during meal times and to avoid using meal replacement shakes as a whole to prevent diluting your stomach acid.

“Digestive enzymes ensure that food substances and nutrients are broken down properly for optimal gut health — our gut is our ‘second-brain,’ connected to our brain by the ‘gut-brain axis,’ so our diet and our gut are the starting point for all health goals,” she told HuffPost. “Chewing is also important for the release of stomach acid. If your stomach acid is too low, you can find yourself with indigestion and other gut issues, including bloating.”

Another concern that dietitian, as Nichola Ludlam-Raine told Live Science, is that the fiber levels in meal replacement shakes are normally below the advised daily amount and much lower than a solid meal would provide.

It is common for people to experience constipation and bloating when they first start drinking liquid meal replacements. Ludlam-Raine advised drinking lots of fluids with the shakes to combat constipation.

“It’s recommended to aim for at least 1.5 liters of fluids on top of the shakes to promote regular bowel function. You may also want to aim for one piece of fruit or veg in each of your three recommended snacks and two handfuls of veg in your evening meal to boost your fiber intake,” she said.

Most meal replacement shakes are heavily processed with a long shelf life. If possible, it is more valuable for your health to consume food at its most natural state, Wilkinson advised.