Many popular diets include replacing one or more meals with a drink or shake. At first glance the drinks may seem like a good substitute for breakfast or lunch to shed some unwanted pounds, but many of them are full of sugar and lack the essential building blocks of a complete meal.
Too much sugar
Taking a look at three of the most popular meal replacement drinks, all three have more than 28 grams of carbohydrates per serving. Special K Shakes have 29g, Boost has 33g, and Carnation Breakfast Essentials has 34g. Put another way, anywhere from 56 – 65% of total calories are coming from sugar. These drinks have very little fibre in them as well. These things together cause huge spikes in blood sugar, resulting in mood swings, headaches, and food cravings. Since there is no fibre or solid material for the body to have to digest, the sugar is metabolized very quickly, overwhelming the liver and pancreas.
There is also the possibility of artificial sweeteners in these drinks. Sugar substitutes are chemical compounds that are many times sweeter than sugar, and can be very harmful to the body. There is research to suggest that consuming too many artificial sweeteners can disrupt taste buds and cause a dislike of foods that do not have that same level of sweetness.  The same research also contends that the sweeteners can change the way the body associates sweetness with hunger and fullness, causing a person to consume many more calories than necessary to feel full.
Lack of vitamins
These drinks are so highly processed that almost all vitamins and minerals are stripped away. A person eating a balanced diet will get the vitamins that he or she needs from the variety or fruits, vegetables, grains, and proteins eaten on a daily basis. Replacing a meal or two with shakes that are devoid of these essentials can quickly deplete the body’s stores and lead to critical deficiencies. Symptoms like low energy, brittle nails, and sallow skin are early warning signs of a serious lack of vitamins.
Meal replacement drinks may seem like a quick way to drop a few pounds, but you will probably find that you have more cravings, headaches, less satisfaction with your meals, and symptoms of vitamin deficiency. A balanced diet that includes a wide variety of grains, protein, fruits, and vegetables is the healthiest way to lose weight and keep it off for the long term.