Glucagon-like peptide-1 (GLP-1) injections, aka the fat loss injections, are hot news right now in diabetes and weight loss communities.
In this newsletter, we’ll look at the fascinating science behind these “wonder” drugs, and discuss why it may be better to hit the gym and eat more protein than to start using these injections.
The Science Behind GLP-1 Medications
GLP-1 is a hormone that is naturally produced in our small intestines when we eat carbohydrates or fats. It can also be stimulated neurally (i.e. by our nervous system) and by other hormones.
Its overall function is to help regulate blood sugar levels by a variety of mechanisms:
Increases the production of insulin
Insulin is a hormone released by the pancreas in response to rising blood glucose levels. GLP-1 tells the pancreas to produce more insulin when we eat to help keep the spikes in blood glucose in check.
Blocks glucagon release
Glucagon is another hormone released from the pancreas. It acts on the liver, telling it to break down its stores of glycogen into glucose and release it into the bloodstream. It also triggers glucose to be made from amino acids and lactate. The effect is to increase blood sugar. So by the blocking action of GLP-1, this doesn’t happen and so allows blood glucose levels to stabilise.
Slows gastric emptying
GLP-1 interacts directly with the smooth muscle of the stomach and indirectly with the gut’s nervous system to inhibit the contractions of the stomach muscles, which slows down the speed at which the stomach contents can pass through. This increases the sensation of fullness, reducing appetite and allowing slower absorption of nutrients causing less of a spike in blood glucose.
Regulates appetite centrally
By acting on specific receptors in the brain, specifically in the hypothalamus, GLP-1 can modulate the activity of neurons (brain cells) and neurotransmitters (signalling molecules in the brain) to suppress appetite.
The Ups and Downs of GLP-1 Meds
The overall effect of GLP-1 is to improve blood glucose regulation with a happy bonus of weight loss. There is also some evidence that shows GLP-1 has some heart health benefits independent of improved blood glucose and weight loss.
While they do offer some great benefits, they come with a cost. These medications can cause some uncomfortable side effects by the very same mechanism by which they provide their benefits.
When gastric emptying is slowed down this can trigger feelings of nausea and even cause vomiting. The function of the gastrointestinal tract can also be affected causing diarrhoea or constipation in some people.
The Muscle Loss Conundrum
Having side effects is, of course, not pleasant. However, the biggest concern is the adverse effect of muscle loss when using GLP-1 medication.
In studies looking at the effectiveness of these medications, it is clear that significant weight loss can be achieved. However, not all this weight loss is from fat, there is also a loss of lean muscle tissue.
In any weight loss program, there will be some loss of muscle that accompanies the loss of body fat. In a poorly designed program where there is no resistance training or adequate protein intake, it is estimated that 20-30% of the weight loss is from muscle. This would give a ratio of about 3:1, i.e. for every 3kg of fat loss, you would lose 1kg of muscle.
With using GLP-1 medication the ratio of fat to muscle loss is almost 1:1. For every 3kg of fat loss, you would lose almost an equal amount of muscle mass.
This is not exactly ideal, since muscle is essential for healthy metabolism and performance, both physical and mental.
So, how do we avoid this? As with any good weight loss program, by incorporating resistance training and a high-protein diet into our lives. But, this then begs the question…
Why Not Try Resistance Training and a High-Protein Diet First?
It is most likely that those that would need the GLP-1 medications in the first place might not be performing regular resistance training sessions or having protein-packed meals. So why not give these lifestyle changes a go before turning to medication?
As mentioned above, increased muscle mass positively affects your metabolism, making it easier to lose weight and manage blood sugar levels when combined with a calorie-controlled diet. Resistance training also improves heart health, and bone density, and reduces the risk of developing chronic disease.
A high-protein diet has been shown to help preserve muscle mass when on a calorie-controlled diet. As well as being more satiating than carbs or fats meaning that we feel fuller for longer, leading to fewer calories consumed.
The trouble is that making changes to our lifestyle can be challenging to start and establish for the long term. Modern life is busy, with our time and energy being spent on all the various obligations and responsibilities we collect as we get older.
But, if we can make these changes and see the improvements they bring to our health and performance, then we might be able to avoid the need for medication altogether.
Weighing the Pros and Cons for Different Situations
Just to be clear, I am not saying that GLP-1 medications are a bad choice – for certain situations. For those who are diabetic or morbidly obese then these can be a lifesaver. I would advise that, alongside taking the medication, they make sure they undertake regular resistance training and that they hit their daily protein goals no matter what to preserve as much muscle mass as they can.
However, I am seeing a lot of people seeking a prescription for these medications who are not significantly overweight, typically wanting to lose 5 or 6kg to help them achieve a “beach body”. For this group of people, the cons outweigh the pros, especially the loss of muscle mass, and I wouldn’t recommend it.
So before jumping on the GLP-1 med craze, why not give a high-protein, calorie-controlled diet along with regular resistance training a go instead?
