Prevalence of obesity is increasing worldwide. As a result, we are seeing more people with obesity related medical conditions. In the current COVID pandemic, we also noticed that people with obesity and obesity related medical conditions like type 2 diabetes had poor outcomes. We are now in desperate need for effective weight loss medication and I will discuss a new medication called tirzepatide. Lifestyle changes alone clearly are not helping people lose weight in the long run. More people are now aware of what to eat and how to exercise. Despite this knowledge and access to information, people do not lose weight and keep it off.
Medical weight management
Over the last 100 years, weight management involved following a diet, which helped lose weight. This gradually evolved into weight loss groups, where a particular food group was either avoided or promoted. This led to diets like high protein and low carbohydrate diets. People consulted a dietitian for weight management when group interventions did not help. The natural transition, when diets do not work was weight loss surgery. People go straight to have bariatric surgery like sleeve gastrectomy, intragastric balloon, gastric bypass surgery, gastric band and even duodenal switch. When diets fail or they do not respond to diets, people only think about weight loss surgery.
However, in the last 15 years, we have seen several medications approved for weight loss. Some of the medications have been withdrawn due to concerns with safety and some have not been as effective. Orlistat® (Xenical) has been tried by a significant number of people who attend my obesity clinic and most of my patients have reported that either the weight loss benefit was not sustained or they could not tolerate the medication. Sibutramine (Reductil) and rimonabant (accomplia) were both removed from the market due to serious side effects.
In the last few years glucagon like peptide (GLP-1) class of medications like Saxenda® and semaglutide has been licensed for weight management.
Incretins are hormones produced by the neuroendocrine cells in the gut. The main incretins are GLP and GIP (Glucose-dependent insulinotropic peptide). GLP-1 promotes secretion of insulin and has been used in the treatment of type 2 diabetes. There are several medications in this class like Victoza, Bydureon, Trulicity etc.
GLP-1 like medications stimulate the GLP-1 receptors and increase insulin production, reducing hunger by acting on the satiety centre in the brain and also by its action on the gastrointestinal tract.
Semaglutide (Wegovy®) is more effective than Liraglutide (Saxenda®).
How does Tirzepatide help you lose weight?
Tirzepatide is a once-weekly medication and is a combination of the two incretins, GIP (Glucose-dependent insulinotropic polypeptide) receptor and GLP-1 (glucagon-like peptide-1) receptor agonist (positively acts on the receptors).
GIP complements the effect of GLP-1 receptor agonists. GIP has been shown to decrease food intake and increase energy expenditure leading to weight loss. The combined effect of GIP and GLP results in greater weight loss and also has shown to have greater benefit in lowering blood glucose and lipids.
Tirzepatide is being researched for treatment of type 2 diabetes, obesity, Non-Alcoholic steatohepatitis (NASH), Obstructive Sleep Apnoea (OSA) and heart failure with preserved ejection fraction.
How much weight loss is seen with tirzepatide?
In a research involving about 2500 patients with tirzepatide, patients on
Tirzepatide 5mg: Lost 16% weight
Tirzepatide 10mg: Lost 21.4% weight
Tirzepatide 15mg: Lost 22.5% weight
Those who were given placebo in the study only lost 2.4% body weight.
This was a phase 3 clinical trial conducted by the pharmaceutical company El Lilly and the study was called SURMOUNT-1. The duration of the study was 72 weeks.
Most importantly 89% of patients on tirzepatide lost at least 5% body weight.
Those taking tirzepatide 15mg lost 52lbs or 24kg in 72 weeks.
Is Tirzepatide safe?
The trials with tirzepatide are not complete hence the full picture is not known. We however know that the GLP-1 class of medications which has been used for several years for type 2 diabetes and obesity is well tolerated.
More information on its safety and efficacy will be known after the studies are completed and post marketing analysis is done.
Further information on tirzepatide
I will keep you posted as we hear more about tirzepatide and also will update you when this medication will be available.
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Dr Chinnadorai Rajeswaran is a consultant Physician specialising in Endocrinology, Diabetes and Obesity. As a private endocrinologist he has private endocrine, diabetes and weight loss clinics in Harley Street, London, Claremont Hospital, Sheffield, Nuffield Hospital, Leeds and simplyweight, Bradford in the UK and in Chennai, India.
