Everyone is on Weight loss drugs! Should I start one?

A magic bullet is what many people have been looking for in weight loss and it would be wonderful to think that this is finally what we have in this latest round of weight loss medications.  The problem with rapid weight loss is that we tend to lose lean body mass or muscle as well as fat and, as such, our metabolic rate slows down and our hunger signals tend to increase.  This means that once the diet is over and we have achieved our ideal weight, weight regain, in particular regaining fat is rapid and is often over and above where we started.

Whilst this latest round of weight loss medications are the most exciting medications we have seen so far, it is very important to understand that they are not the “quick fix,” or “magic bullet,” they are sometimes thought to be.  However, they can make a profound difference to weight loss if they are combined with significant lifestyle changes.

The class of medications I am referred to are the class of drugs called “GLP-1 (Glucagon Like Peptide -1) agonists”.  They work by mimicking the natural hormone, GLP-1, whose main effects are in the brain and pancreas, controlling appetite and how quickly we metabolise food or how quickly food moves through your stomach, along with helping with blood sugar control. 

There are currently two most commonly used drugs of this type in Australia.  They are called semaglutide (branded as Wegovy or Ozempic), and tirzepatide (branded as Mounjaro).  Tirzepatide is a dual medication that works as a GLP-1 agonist and by imitating another type of hormone called Incretin which binds to insulin like receptors and improves insulin sensitivity and blood sugar control. These medications are all currently administered as weekly injections.

In practical terms, people using these medications feel fuller for longer and usually don’t feel so hungry. The medications also reduce cravings between meals, and you tend to eat smaller meals, so calorie intake is much lower.  These medications also assist in managing blood sugar levels, so energy levels are better throughout the day and additionally reducing the urge to snack.

Side-effects can include constipation, bloating and nausea.  These can be managed by making sure you drink plenty of water and by having smaller, more frequent meals. Sometimes additional medications may be needed to offset the side-effects. It is also important not to rush dose increases, to help minimise side-effects.

Why is diet important if I am losing weight on this medication?

It is especially important to combine these medications with significant lifestyle changes.  Simply reducing your caloric intake alone is not enough to promote long term weight loss.

It is worth considering visiting a dietitian to make sure that what you are eating is providing appropriate amounts of protein for maintain and building good lean body mass and is providing you with enough, calcium, iron, fatty acids and appropriate essential vitamins and nutrients to reduce the risk of cancer, stroke and cardiovascular disease. 

Having a diet with adequate amounts of protein will also help reduce the risk of weight, and particularly, fat regain when you cease the medication.  This is because adequate protein will help you maintain muscle while using the medications. You want to lose fat and not muscle.  Protein also helps your muscles recover after exercise.  Other advantages of a well-balanced diet are that it will reduce the risk of your metabolism slowing during weight loss, as well as preventing the need for a multivitamin supplement during weight loss.  

Why is exercise important if I am losing weight on this medication?

There is a lot of research that has shown that combining these medications with resistance or weight bearing exercise produces the best long-term outcomes in terms of preventing regain of weight, particularly fat.  Doing regular resistance exercise whilst taking these medications prevents rapid muscle loss so that metabolic rate is maintained.  This is because muscle burns more energy than fat so maintaining muscle prevents your metabolism from slowing down.

Exercise in general improves energy and mood, and resistance exercise can help reduce the risk of osteoporosis.

So, what is resistance exercise?

• Lifting weight

• Using resistance bands

• Squats

• Push ups

• Reformer pilates

Regular walking or aerobic activities most days should also be considered to keep your metabolic rate high.

It can be very useful to involve an Exercise Physiologist (EP) in your weight loss journey.  An EP is a university-trained health professional who specialises in exercise for people with medical conditions or specific health goals. They can:

• Design a safe, personalised exercise plan including exercises that do not necessarily involve the gym.

• Monitor your progress and adapt your plan.

• Protect your muscles and joints from injury during exercise

• Assist with motivation!

• Track your weight loss with DEXA (Dual-Energy X-ray Absorptiometry)1 scans, which are scans that can help determine the proportion of muscle, fat and bone composition in your body and can help determine how best to maintain or build muscle mass. A DEXA might be recommended at the beginning of your weight loss journey and then around the 3- and 6-month mark.

Take Home Message

• GLP-1 agonists are very effective weight loss medications when combined with a well-balanced diet and resistance and aerobic exercise.

• It can be expected that people will lose 15 – 20 % of their body weight over 12 – 24 months

• The medications work be reducing appetite, delaying gastric emptying, and helping to control blood sugar.

• Best outcomes can be achieved when you work with a dietitian and exercise physiologist.

• You might want to consider a DEXA scan to monitor your fat and muscle during your weight loss.

• You may also get an improvement in their blood pressure, blood sugar, cholesterol, resulting in a reduced risk in cardiovascular disease, diabetes, and malignancy.

• The main side effects of the medications are nausea, constipation and bloating.

• There is a small risk of pancreatitis.

• Mounjaro carries a thyroid cancer warning and should be used cautiously if there is a personal or family history of the disease.

• These medications aren't covered by the PBS, so they are costly and paid out-of-pocket.  Sometimes, a rebate can be sought from private health insurance.

Note 1: The DEXA scans referred to here are different from the DEXA machines used specifically for bone mineral density (BMD) scans, which must be done through a dedicated radiology service.