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The Role of Meal Replacements for Weight Management in the Era of Semaglutide and Tirzepatide

While weight management medications are not new, they have evolved so that more people are taking them and more people will take them as coverage and supply improves. Semaglutide and tirzepatide (Ozempic, Wegovy, Mounjaro, Zepbound), while only covered for about 40% of the population and currently really hard to find in the pharmacies, are game changers for many people. As of now, it is estimated that 14% of the adult population is taking one of them. Is there still a role for meal replacements if you are taking one? Let’s look at some of the reasons I believe there is still a crucial role for medical foods and while I use them in combination with weight management medications to optimize results.

Semaglutide at a dose of 1 to 2 mg a week shows an average of 15% weight loss in one year. Tirzepatide shows an average of 20% weight loss at one year. A gastric bypass surgery shows an average of 30% weight loss. The point is, these medications do not cause a loss of all the excess body weight, on average. For example, if a person starts at 250 pounds, and their ideal body weight is 160 lbs, on tirzepatide, their weight loss would be an average of 20%, or 50 pounds, which results in a weight nadir (lowest weight achieved) of 200 pounds. So, if you want to give yourself the best chance of losing the most excess weight and keeping it off, or you feel you are reaching a plateau or your weight loss is slowing down, using medical foods as meal replacements may help. Studies show that the more weight a person loses in the first 6 months, the lower their maintenance weight will be.

With weight loss, people tend to lose muscle and fat. Losing muscle, if you do not have extra to spare, is not good for you. Losing muscle reduces your resting metabolic rate and may reduce bone density, especially over time. Muscle has favorable effects on the metabolism .Muscle increases insulin sensitivity and stores glycogen in a healthy way so it does not clog up your liver. It also helps you be able to do cool things like hike up a mountain and lift heavy things and helps prevent loose skin people don’t like when they lose weight. When people lose weight with calorie restriction and exercise, an average of 20% of the weight lost is lean body mass. When people lose weight using medical food meal replacements, only 10% of the weight lost is lean body mass, on average. On the contrary, in the study of semaglutide for weight loss, an average of 30% of the weight lost was lean body mass. Why is that? Perhaps people were not eating regularly throughout the day and did not get adequate protein in the small amount of food volume they were eating. If you use meal replacements while on a weight management medication, you get a lot of protein and vitamins in a small volume. They are designed to give you total required nutrition, not just supplement your protein intake like over the counter protein drinks. This can prevent the sarcopenia (low muscle) that is frequently seen after a person loses a large amount of weight, such as with bariatric surgery, which has been associated with weight cycling and even osteoporosis and fragility fractures.

Many people have lost weight many times, only to have it come back. Metabolic adaptation to weight loss describes why. When people reduce their body weight, their metabolic rate goes down, and it goes down by more than expected for their new given weight. What does this mean? Well, if you enter your height and weight into any nutrition app, it will spit out the number of calories you need to eat in a day. This is a standard calculation that is applied to everyone the same way. When you put in your starting weight and then your new weight, you will see that it says you should eat fewer calories at your new weight. This is simple physics. It takes less energy to run something smaller than something bigger. However, studies show that when people have arrived at the new, lower weight after weight loss, as opposed to it being their natural weight set point, their actual metabolic rate is lower than another person of the same height and weight. Part of this is from the loss of lean body mass. So, if you use medical food meal replacements and optimize your lean body mass, your new metabolic rate will be higher. This helps with the tendency to regain weight and gives you more room in your calorie intake. In metabolic adaptation to weight loss, people also experience more hunger and cravings than before losing weight, because their body “thinks” it is underweight. Meal replacements can help by keeping hunger to a level where making choices is more manageable, as opposed to being so hungry that most people will eat whatever is available.

Some of the most common side effects noted on these weight loss medications are nausea or an upset stomach. This comes primarily from their tendency to slow down stomach emptying. This tends to be worsened when a meal is either higher in volume or higher in fat When the stomach “stretches” or fills with food, it causes you to feel “full”. This effect can be magnified to the degree that a person feels sick and can lead to a person skipping meals or going long periods of time with no nutrition. Meal replacements are a lot of nutrition and vitamins in a small package, so you can get everything you need without stretching the stomach. They are also very low in fat. When a person eats fat, it also causes the stomach to slow down. Eating a low fat diet can reduce the stomach upset. Meal replacements are a way to do that and also be low in sugar at the same time. One of the more serious potential side effects of these medications is acute kidney injury, which happens when a person does not eat and drink enough so they get dehydrated and undernourished. While rare, and most often when a person is on a water pill or blood pressure pill, it may be an illustration of the risk of not getting adequate nutrition while in a calorie deficit. Some people report fatigue on these medications, even though they should not cause that based on how they work. Perhaps that is from simply not getting great nutrition while they are on them and not eating very much.

The very low calorie ketogenic diet / protein sparing modified fast has shown great results with weight loss by losing a large percentage of the “sick fat” in the trunk and viscera while relatively preserving lean body mass. The challenge has been weight regain and durability of results. The same is actually true of weight loss with medications and surgery: weight regain seems to be a significant risk no matter how a person loses weight. These new generation weight loss medications may be more important for improving tolerability of the program and for preventing weight recurrence, and using them together may be the best of both worlds for the optimal result of losing unhealthy fat while preserving lean body mass and then keeping it that way. Even with weight loss medications, and perhaps especially while on them, how you nourish your body is crucial, not just the amount. These medications have only been used to treat obesity for a short time. Using the tools together, including a balanced exericse plan, may be the ticket to reaching the healthiest body composition and maintaining it.

We recommend monitoring your body composition and blood work during any weight management program to get the best individual results and optimal program for you. Reach out and let us know if you would like to get your body composition measured and learn more.

We do not know the long term outcomes yet, so let’s do everything we can to get the best chance for the best long term results. They have been used to treat Type 2 Diabetes for longer, but the physiology of someone with Type 2 Diabetes is not the same as someone without it, which may explain some of the variability in tolerability and results. I don’t think it’s time to throw out meal plans yet.

Take Back Your Meal Plan,

Valerie Hope-Slocum Sutherland, MD

Diplomate, American Board of Internal Medicine

Diplomate, American Board of Obesity Medicine

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