Tirzepatide is a dual acting drug which mimics the action of glucagon like peptide-1 (GLP-1 RA) receptor agonist and glucose dependent insulinotropic polypeptide (GIP). It helps in weight loss by:

  • Increasing energy expenditure

  • Decreasing energy consumed through food

This drug was initially approved for the management of blood sugar levels in individuals with type 2 diabetes mellitus and now it is also approved for weight loss.

Obesity is a chronic illness which contributes to mortality and morbidity rates worldwide. The metabolic complications of obesity are – hypertension, heart disease, diabetes, fatty liver etc., which may be further complicated by being overweight or obese. Slimming or weight loss helps reduce development of these weight related medical conditions.

The trade name for tirzepatide is Mounjaro and in some other countries is marketed as Zepbound

A 3 phase trial conducted on adults in 2022 revealed an average weight loss of 19.5% and 20.9% with 10mg and 15mg doses of tirzepatide respectively.   

How does Mounjaro or Zepbound work? 

Mounjaro promotes weight loss by suppressing appetite and promoting satiety. This has a dual mode of action through the help of GIP and GLP-1 RA (incretin hormones released in the gastrointestinal tract after the consumption of food). GIP and GLP-1 RA stimulates the pancreas to produce insulin and stops the breakdown of glycogen in the liver (glycogenolysis).

There are other weight loss drugs such as Wegovy and Ozempic, available in the market but tirzepatide is assumed to be more effective due to the property of its dual action capacity. 

According to the National Institute of Health and Care Excellence (NICE), tirzepatide like Mounjaro must be chosen as an alternative for semaglutide. 

Expected weight loss on tirzepatide

A study was conducted on 2539 adults with a BMI greater than 30 kg/m2 or BMI >27 kg/m2 + 1 weight related medical condition. They were given three doses – 5mg, 10mg or 15mg doses of tirzepatide with a lifestyle intervention. The result was a decrease in baseline weight by a minimum of 5%. 

All about Mounjaro

Mounjaro is an FDA approved trade name of the drug tirzepatide by Eli Lilly and company. It is an injectable drug used for adults with type 2 diabetes to improve blood glucose levels and for weight loss.

The criteria for use of Mounjaro (tirzepatide) in people with type 2 diabetes and/or obesity:

  • Adults with uncontrolled type 2 diabetes mellitus after ineffective treatment with 3 or more hypoglycaemic agents caused due to intolerance or contraindication.

  • Individuals with a BMI greater than 30 kg/m2 or those with a BMI of 27 kg/m2 with a weight related medical condition (comorbidities – diabetes, hypertension, hyperlipidaemia, obstructive sleep apnoea (OSA), heart attack, stroke, and blood vessel disorders).

  • Individuals with < 35 kg/m2 with probable complication to insulin therapy.

  • Probable improvement in weight related issues due to weight loss.

  • Note – A lower BMI (reduced by 2.5 kg/m2) threshold is used for individuals of South Asian, Chinese, other Asian, Middle Eastern, Black African or African Caribbean family backgrounds.

However, There isn’t sufficient information regarding the use of tirzepatide (Mounjaro) in the treatment of 

  • Individuals with type 1 diabetes.

  • Children (less than 18 years of age).

  • Pregnant and lactating women

  • Individuals with a family history of pancreatitis.

  • Senior citizens (above 75 years of age).

Side effects and unwanted effects of tirzepatide

  • Risk of loss of lean mass – There is a possibility of the loss of lean muscle mass over fat due to the action of tirzepatide. According to a study conducted on 178 participants on metformin and a weight loss drug, there was a significant loss of fat mass accompanied by a loss of a proportion of lean mass. However, individuals who are obese may store a certain portion of fat in the skeletal muscle, there is inadequate information about the portion of loss of fat from lean mass.  

  • Muscle loss is also seen with most weight loss interventions including other weight loss medications. Loss of muscle mass is called sarcopenia.

  • Weight rebound – Continued treatment with weight loss drugs is needed to ensure sustainable weight loss with a good diet and healthy lifestyle.

  • Gastrointestinal side effects – The common side effects of tirzepatide are similar to those induced by GLP-1 RA. The intensity of the side effect depends on the dosage of Mounjaro (tirzepatide) the individual is on.  

Some of the common side effects include:

  • Nausea and vomiting 

  • Diarrhoea 

  • Reduction in appetite 

  • Heartburn

  • Stomach pain

  • Bloating

  • Burps

  • Constipation

  • Tiredness

  • Low blood sugar levels

  • Vivid dreams

  • Hair loss

The side effects of semaglutide (Wegovy) are similar. 

Dietary modification can help with certain gastrointestinal symptoms.

Uncommon side effects and risks 

The uncommon side effects and risks of tirzepatide (Mounjaro)  are –

  • Thyroid C-Cell tumours – very rare, seen in rat models with GLP-1 medications

  • Pancreatitis

  • Hypoglycaemia

  • Hypersensitivity

  • Acute kidney injury

  • Gastrointestinal issues

  • Diabetic retinopathy 

  • Gallbladder diseases


Tips for weight loss with Mounjaro


Weight loss is a long term process. The type of food included in the daily diet and lifestyle followed are still important when on weight loss drugs like tirzepatide (Mounjaro). 

  • Do not skip meals – Skipping meals can lead to hypoglycaemia manifested as dizziness and fatigue etc.

  • Have a protein rich diet – Consuming a diet rich in protein like eggs, poultry, fish, beans and legumes, etc., can help preserve muscle mass and promote fat loss.

  • Increase physical activity – Physical activity can help in improving muscle strength and avoid muscle loss.

  • Drink plenty of fluids – Water is very important to filter toxins from the body, avoid dehydration and possibly improve the metabolic rate. Drinking water may also help with excessive hunger.

  • Consume whole grains over refined grains – Whole grains like quinoa, brown rice, red rice, couscous are rich in fibre and B vitamins which may improve satiety while simultaneously stabilising blood sugar levels since they are low in glycaemic index.

  • Include seeds and nuts – These are rich in essential micronutrients like zinc and magnesium which helps in satiety and immunity.

  • Consume plenty of vegetables and some fruits – Fruits and vegetables which are low in glycaemic index are green leafy vegetables, non starchy vegetables, berries, pears etc. Low glycaemic index fruits and vegetables like corn, roots and tubers like carrots, potatoes, etc.

  • Avoid processed and fried food – These foods are high in calories like trans fat and saturated fats which are harmful to health. They may further trigger gastrointestinal symptoms.

  • Avoid sugary food and aerated drinks – Such food are higher in calories and have no nutritive benefits. They may spike the blood sugar levels and cause bloating and indigestion.

  • Avoid alcohol consumption and smoking – Consumption of alcohol along with tirzepatide can lead to side effects including hypoglycaemia (low blood glucose) and dehydration. Hypoglycaemia is more common when you are on insulin or medications like Gliclazide/Glimepiride.

Note

  • Do not reconstitute insulin and Mounjaro in the same injection.

  • The area of injecting Mounjaro and insulin can be the same area of the body but next to each other.

  • The minimum duration between 2 doses of Mounjaro must be 72 hours. .

  • The day of injection can change per week based on the duration or gap of 72 hours suggested.

  • A missed dose of Mounjaro can be taken on the regular scheduled day if more than 4 days after the original day of injection.

  • Always consult a physician before starting Mounjaro (tirzepatide). 

  • Follow the instructions of a registered medical practitioner regarding the right way to use the drug.

  • Mounjaro is an effective weight loss medication when combined with lifestyle changes.