best diet shake

RightSize Diet Shake Review – Digging Into This Weight Loss Shake

“Simple, delicious, nutritious” – it’s a catchy slogan paired with clever marketing that makes this meal replacement shake sound appealing and effective. Who doesn’t want a “hunger smashing” weight loss smoothie to help stave off hunger and keep you full for hours? Digging deeper, however, reveals there’s more to this shake than meets the eye. We’ve researched the ingredients and dug into their clinical study to find out the truth. Here, we’ve collected the data for you to read and make your own decision about whether RightSize diet shake is a healthy choice for you.

RightSize Nutritional Facts

A look at the nutrition facts on any RightSize shake quickly begins to unravel some of the company’s claims of being “packed” with protein and fiber. With each 29-gram serving, the shake only offers 7 grams of protein. This is the lowest we’ve seen in any shake claiming to be a high-protein meal replacement shake. That fact combined with the relatively high amounts of sugar, this shake’s balanced nutrition is certainly called into question.


One good thing RightSize has going for it is the calorie count. At 100 per serving, it’s reasonable and certainly helps promote weight loss. However, in order to get adequate protein, the serving size has to be doubled or the powder must be combined with milk. This increases the calories to 180 when using fat free milk, but does provide 15 grams of protein.


Controversial Ingredients

Unfortunately, reading through the RightSize ingredients list reveals more than just a few controversial components to this shake. While claiming to be “packed” with vitamins, minerals, protein, and fiber, RightSize also has questionable ingredients that may do more harm than good in the long run.

To start with, soy is the primary protein used in RightSize. We’ll go into more detail about this later, but let it suffice to say this is a questionable protein source that many health experts recommend steering clear of.

Maltodextrin is listed as the third ingredient in RightSize. This substance is a food additive made from grain starches, most commonly corn[i]. It’s used to stabilize, sweeten, and thicken packaged foods. While it is highly processed, maltodextrin is still a naturally derived additive. In small amounts, maltodextrin isn’t necessarily harmful. What’s bothersome about its use in RightSize is the fact that it’s listed as the third ingredient, meaning it’s found in a relatively high quantity in the food.

Crystalline Fructose is used to sweeten RightSize. This sweetener is derived from corn and has such concentrated sweetness it can add flavor with fewer calories, thus making it attractive to companies producing products marketed to the health-conscious. However, the repercussions of consuming this sweetener aren’t worth the calories it saves you. Fatty liver disease, hyperlipidemia, coronary disease, and obesity are just a few of the unpleasant side-effects crystalline fructose can cause[ii].

Canola Oil is made from a genetically modified version of the Rapeseed plant. Often touted as a “healthy oil,” it does have low amounts of saturated fats and high amounts of unsaturated fats (the good kind of fats), including Omega 3 fatty acids. But, industrial production of canola oil utilizes processing methods that include dangerous chemical washes and exposure to heat that oxidizes the oil. One study also found up to 4.2% trans fat in canola oil[iii].

The artificial flavors listed on the label are mysterious chemical mixtures that imitate a natural food flavor[iv]. These synthetic ingredients aren’t natural at all, and are often chosen by manufacturers to save on time and money in the creation of their product.

Silicon Dioxide is a compound used in food to prevent caking[v]. A variety of products incorporate it, from drugs to supplements to printer toners to cosmetics to insecticides. Although the U.S. Environmental Protection Agency categorized Silicon Dioxide in Toxicity Category III, the FDA considers it to be safe based on the fact that most people will consume a small enough amount they will never experience a negative impact on their health[vi]. However, the fact remains that silicon dioxide in significant quantities is harmful.

Acesulfame Potassium (also known as acesulfame K) is an artificial sweetener. 200 times sweeter than table sugar, acesulfame potassium is not metabolized or stored in the body. Ones you consume it, your body absorbs but then excretes it unchanged[vii].

Protein Sources

RightSize diet shake uses soy as protein. While the unimpressive 7 grams offered in a serving isn’t much, consuming soy for protein is still not advisable. Due to demand, soybeans have become one of the most highly genetically modified crops also highly contaminated by pesticides. From a health standpoint, soybeans have enzyme inhibitors that actually block your body’s ability to properly digest protein[viii]. On top of that, the phytic acid naturally found in soybeans prevent the body from absorbing essential minerals.

Fiber Sources

At 6 grams of fiber, RightSize shakes got that part right. That’s enough to satiate you and likely will help this shake stave off hunger until your next meal or snack.

What Are the Sweeteners?

As we’ve mentioned, RightSize uses crystalline fructose to sweeten the diet shakes. Yes, fructose is a naturally occurring sugar found in plants (namely fruits and vegetables), so in some ways it may be a better option than artificial sweeteners. The allure of fructose is that it doesn’t affect the human body the same way glucose does. This means it doesn’t cause spikes in blood sugar and has fewer calories. However, this same fact – that it isn’t metabolized the same way as glucose – is the reason it’s dangerous.

Our bodies run on glucose, which means when we consume it, much of the glucose is immediately used to fuel the cells in our bodies. Fructose, on the other hand, can only be metabolized by the liver, which is easily overloaded. When this happens, the fructose is turned into free fatty acids, VLDL (bad cholesterol), and triglycerides, all of which are stored as fat[ix].

Even though fructose is a lower-calorie sweetener, RightSize still has 6 grams of sugar per serving, making us think this shake is extremely sweet for a “healthy” meal replacement.

In addition to crystalline fructose, RightSize also uses the artificial sweetener acesulfame potassium to further sweeten the beverage. It’s a potassium salt partly comprised of methylene chloride, which is known to cause cancer.

Who’s Behind RightSize?

The RightSize website is suspiciously sparse on any information about the company itself. However, it seems RightSize is linked with a company called Insight Beverages that manufactures a whole variety of other beverage products.

Side Effects

Crystalline fructose may be responsible for contributing to fatty liver disease, coronary arterial disease, and obesity[x]. Silicon Dioxide has been said to contribute to causing diseases such as rheumatoid arthritis, autoimmune diseases, and chronic kidney disease. Maltodextrin has the nasty reputation of negatively impacting your gut bacteria.

Canola oil’s contributes trans fats, which are notoriously linked to weight gain, inflammation, and heart disease[xi]. This oil has also been shown to cause lung cancer, disrupt the central nervous system, cause respiratory illness, anemia, and constipation[xii].

The shake’s protein source, soy, has unfortunately been linked with a whole list of negative health issues. One of the biggest impacts soy has on the human body is on the thyroid. The goitrogens in soy block the production of thyroid hormones. Soy protein isolates have been shown to enlarge the thyroid. Soy may also increase fatty acid in the liver.

How To Contact

The RightSize website lists an address at 750 Oakwood Road in Lake Zurich, IL (60047). The only way to actually get in touch with the company is by emailing them through a form provided on the Contact page[xiii].

Product Returns

We can’t say for sure. The RightSize website doesn’t list a return policy at the time of this review. It seems inquiries should be addressed to the company through their contact form.

Other Products By RightSize

While it seems RightSize used to make other products in the past, their website currently only lists the RightSize meal replacement shake, which comes in four flavors: Lean Cocoa Bean, Skinni Vanilli, Slend-A-Berry, and Leano Cappuccino.

Does it Work?

The strategy for RightSize is similar to many other meal replacement shakes: drink the diet shake for two meals a day, eat a couple low-calorie snacks, and eat a reasonable dinner. Following this plan means you’ll probably be eating fewer calories than your normal diet, which means you will begin shedding pounds. However, the nutrition contained in the diet shakes is questionable. While they do have a clinical study available to look at that claims participants lost up to 18 pounds in 12 weeks, the fact is only 28 of the 55 participants finished the study. It seems the shakes alone simply don’t have the nutrition necessary to be sustainable.