Replacing meals with shakes never works long term

No. Across 23 trials with 7,884 adults, people on diets that replaced some meals with products like shakes and bars lost about 3 lb (1.44 kg) more at one year than people on other diets. The shakes took the place of meals. No trial tested a shake added on top of meals, or a homemade glass.

Why people believe it

Most people have heard of a liquid diet that didn’t last. There are the crash diets of the past, the shake plans that leave you starving, and the friend who lost weight on shakes and gained it back. It feels like the kind of quick fix that can’t work over time. The authors of the biggest review note that clinical guidelines for obesity generally don’t recommend meal replacements.

The trials say otherwise, as long as you’re clear about what “meal replacement” meant in them.

A fixed menu at lunch

A meal replacement works a bit like a fixed menu at lunch. You know exactly what you’re getting and how much, and you don’t have to decide or count every day. A homemade glass can copy that, as long as it’s the same recipe most days.

What the trials found

In the Oxford review, a meal replacement meant a product used in place of at least one meal a day, with at least one ordinary meal kept. That included shakes, bars, soups and portion-controlled meals. Some trials replaced two of the three main meals with shakes or bars. Nerys Astbury and her colleagues concluded that programs with meal replacements “should be considered as a valid option” for weight loss.

In place of a meal

Every trial in the review swapped meals out. None added a shake on top of a normal day. The soda study shows why that’s the line. Calories you drink alongside your usual food tend not to make you eat less of anything else, so they stack up.

That’s the rule we build the whole site around. A smoothie is a meal or nothing. Have it as breakfast or lunch, and keep it out of the gap between them.

The best case for the myth

The skeptics have fair points. About 3 lb more at a year is a real result, but it’s modest, and the range runs from under 1 lb to about 5.5 lb. The review measured weight at one year, so it doesn’t tell you what happens at five. The biggest gap, 6.13 kg, came with extra coaching, so the coaching did part of the work. And the products were packaged, with the same calories every time. No trial tested a homemade smoothie, where the recipe can drift.

We think a homemade glass can do the same job if it’s built like the ones in the trials: the same recipe most days, protein at your meal line (30 g at 165 lb, and the Gyroscope app personalizes yours), and a meal’s calories. How to use a smoothie to lose weight has four glasses that fit a 1,600 calorie day, and bodyfat.guide’s protein calculator gives your range for the whole day, so you keep muscle while you lose.