GLP-1 and GIP Weight-Loss Medications: Benefits, Risks, and What You Should Know

Katrin Peo
3 hours ago
9 min read

In recent years, medications targeting the hormones GLP-1 and GIP have gained significant attention for their ability to support weight loss and improve blood sugar control.

These medications are increasingly used in the treatment of obesity and type 2 diabetes, and for many individuals they can be a powerful medical tool that improves health and quality of life.

At the same time, their rapid rise in popularity has raised many questions:

What exactly are GLP-1 and GIP medications?
How do they work in the body?
Who prescribes them?
What role do nutrition and lifestyle changes play?

Why I Am Writing About GLP-1 and GIP Medications?

As a nutrition counsellor, I often hear questions and discussions about these medications. Many people are curious about how they work and whether they might be appropriate for them.

I have attended several seminars and professional training courses where weight-loss medications were discussed as part of the broader topic of obesity treatment and metabolic health.

Based on what I have learned from these training courses and from current scientific literature, I wanted to share a clear and balanced overview of this topic.

The goal of this article is not to provide medical advice, but to explain what GLP-1 and GLP-1/GIP medications are, how they work in the body, and why nutrition and lifestyle still play an important role when these medications are used.

This article provides a general overview of these medications, their physiological effects, potential benefits, and important considerations related to nutrition and lifestyle.

Note: This article is intended for educational purposes only and does not replace medical advice. Weight-loss medications must always be prescribed and supervised by a qualified physician.

Obesity Treatment Is Multifactorial

Modern obesity treatment rarely relies on a single intervention. Instead, it usually involves a comprehensive and individualised approach, which may include:

nutrition therapy
physical activity
behavioural counselling
pharmacotherapy (medications)
medical devices or procedures
bariatric surgery in some cases

Medications such as GLP-1 receptor agonists and dual GLP-1/GIP agonists are therefore one component of obesity treatment — not a replacement for lifestyle changes.

What Is GLP-1?

GLP-1 (glucagon-like peptide-1) is a hormone naturally produced in the body that plays an important role in regulating blood sugar, digestion, and appetite.

It is released from specialised cells in the intestine—called enteroendocrine L-cells—in response to food intake. After a meal, GLP-1 levels in the bloodstream can increase two to four times, triggering several metabolic processes that help the body manage energy and nutrient intake.

GLP-1 contributes to metabolic regulation by:

stimulating insulin secretion
reducing glucagon release
helping regulate blood sugar levels
slowing stomach emptying
increasing feelings of fullness after eating

Interestingly, natural GLP-1 has a very short half-life of only 1–2 minutes, because it is rapidly broken down by the enzyme DPP-4. Despite this short lifespan, it plays a powerful role in appetite regulation and metabolic health.

Gut Hormones and Appetite Regulation

Although GLP-1 has recently gained widespread attention due to modern weight-loss medications, it is important to remember that it is part of the body’s natural appetite-regulation system.

Inside the digestive tract are specialised hormone-producing cells known as enteroendocrine cells. While they make up only about 1–2% of the intestinal lining, they produce a wide range of signalling molecules that help regulate digestion, metabolism, and hunger.

Among the most important of these hormones are GLP-1 and peptide YY (PYY), both produced by L-cells in the intestine.

These hormones work together to help regulate appetite and digestion. They communicate with the brain to signal that we have eaten enough, slow the rate at which food leaves the stomach, and support digestive processes needed to break down nutrients. PYY, in particular, travels through the bloodstream to the brain where it contributes to feelings of satiety and reduced appetite.

Importantly, the release of these hormones is influenced by what we eat. Meals that contain adequate protein, fibre, and healthy fats tend to stimulate greater release of GLP-1 and PYY.

In addition, beneficial gut bacteria produce short-chain fatty acids when they ferment dietary fibre. These compounds help support the activity of enteroendocrine cells and may further promote the production of appetite-regulating hormones.

In other words, the body already has built-in biological mechanisms that help regulate hunger and fullness. While medications can enhance these pathways, balanced meals that include protein, fibre-rich plant foods, and healthy fats support the body’s natural satiety signals.

You can find multiple articles on protein, healthy fats and fibre in my blog, why they are important for healthy functioning of our bodies, how much we need and the food sources.

👉 I have also created two downloadable resources on how to get 30g of protein in one meal and 30g of fibre in a day.

What Is GIP?

GIP (glucose-dependent insulinotropic polypeptide) is another hormone involved in metabolism.

It is produced by K-cells in the small intestine and released when we eat, particularly in response to carbohydrates and fats.

GIP contributes to metabolic regulation by:

stimulating insulin secretion
helping regulate blood glucose levels after meals
influencing how nutrients are stored in the body

In fact, GIP is responsible for around 60–80% of the insulin response after eating, making it one of the key hormones in the body’s incretin system.

How GLP-1 and GIP Medications Work

Medications have been developed to mimic or enhance the effects of these hormones.

GLP-1 receptor agonists and dual GLP-1/GIP agonists can:

stimulate insulin secretion
suppress glucagon release
slow stomach emptying
interact with appetite-regulating centres in the brain
increase feelings of fullness

As a result, many people experience:

reduced appetite
earlier satiety during meals
fewer food cravings
reduced “food noise” or constant thoughts about eating

Studies show these medications may reduce daily energy intake by approximately 16–39% compared with placebo.

Who Prescribes These Medications?

GLP-1 and GLP-1/GIP medications are prescription medicines.

They are typically prescribed by:

endocrinologists
diabetologists
obesity medicine specialists
general practitioners trained in obesity management
family doctors (especially for repeated prescriptions)

Doctors may consider prescribing these medications when:

BMI is 30 or higher, or
BMI is 27 or higher with weight-related health conditions, such as type 2 diabetes, hypertension, sleep apnea, or metabolic syndrome.

The decision to start medication is always individualised and patient-centred, taking into account overall health, medical history, lifestyle factors, and treatment goals.

These Medications Can Be Life-Changing

For people living with severe obesity, GLP-1 and GIP medications can significantly improve health outcomes.

They may help reduce risks associated with:

type 2 diabetes
cardiovascular disease
fatty liver disease
sleep apnea
mobility limitations

For some individuals, medication can even reduce the need for bariatric surgery.

For these patients, weight-loss medications are not simply cosmetic treatments—they can be an important medical therapy.

Potential Side Effects

Like all medications, GLP-1 and GIP drugs can have side effects.

The most common ones involve the digestive system and may include:

nausea
vomiting
constipation
diarrhoea
digestive discomfort

These symptoms are most common when starting treatment or increasing the dose.

Gradual dose increases are often used to help reduce these side effects.

Below is a general overview of current weight-loss medications.

Weight-Loss Medications

Medication	Active Ingredient	Mechanism of Action	EU Status	Side Effects
Wegovy	Semaglutide	GLP-1 receptor agonist	Approved; 7.2 mg dose under review	Nausea, digestive tract issues
Saxenda	Liraglutide	GLP-1 receptor agonist	Approved	Nausea, digestive tract issues
Mounjaro / Zepbound	Tirzepatide	GLP-1 + GIP receptor agonist	Approved as a diabetes medication; under review for weight loss	Nausea, gastrointestinal side effects
Ozempic / Rybelsus	Semaglutide	GLP-1 receptor agonist	Approved for diabetes treatment	Nausea
Mysimba / Contrave	Naltrexone + Bupropion	Central nervous system effect and reduction of hunger signals	Approved	Mostly mild to moderate gastrointestinal side effects
Orlistat (Xenical / Alli)	Orlistat	Gastrointestinal lipase inhibitor	Approved (prescription Xenical; over-the-counter Alli)	Steatorrhea, fatty diarrhea

Source: Tallinn Healthy University of Applied Sciences, Laine Parts

Reduced Appetite and Nutrient Intake

One of the key effects of GLP-1 medications is a significant reduction in appetite.

While this contributes to weight loss, it can also lead to lower overall nutrient intake.

Studies suggest that energy intake may decrease by 16–39% during treatment.

If diet quality is not carefully managed, this may increase the risk of nutrient deficiencies, especially when daily quality food intake drops below approximately:

1200 kcal/day for women
1800 kcal/day for men

Nutrients that may become insufficient include:

iron
calcium
magnesium
zinc
vitamins A, D, E, and K
vitamin B1
vitamin B12
vitamin C

Possible signs of deficiency may include fatigue, hair loss, muscle weakness, poor wound healing, or unusual bruising.

You can learn more about the important roles of all vitamins and minerals in our bodies from my downloadable resources.

Muscle Loss During Weight Loss

Another important consideration is loss of muscle mass during rapid weight loss.

Research shows that during significant weight loss:

about 60% may come from fat mass
up to 40% may come from fat-free mass, including muscle

Muscle loss may be more likely in individuals who:

consume insufficient protein through their diet
are physically inactive
are older adults
are peri- or postmenopausal women

Maintaining sufficient muscle mass is important for:

metabolic health
strength and mobility
long-term weight maintenance
healthy ageing

Protecting Muscle Mass: Protein and Exercise

Two factors are particularly important during weight loss treatment.

Adequate protein intake

During active weight loss, protein intake may need to increase to roughly:

1.2–1.6 g of protein per kg of body weight per day.

Good protein sources include:

fish and seafood
eggs
dairy products such as yoghurt or cottage cheese
legumes and beans
nuts and seeds
lean poultry

Strength training

Resistance exercise is essential for preserving muscle mass.

Many experts recommend:

strength training at least 3 times per week
150 minutes of moderate aerobic activity per week

Exercise also improves insulin sensitivity, cardiovascular health, and metabolic function.

Nutrition Still Matters

Even when medications reduce appetite, diet quality remains extremely important.

A nutrient-dense diet during treatment should emphasise:

vegetables and fruits
whole grains
legumes
nuts and seeds
quality protein sources
healthy fats such as extra virgin olive oil, avocado, nuts and seeds

It is recommended to limit:

refined carbohydrates and processed grains (white flour products (pasta, white bread), white rice etc)
sugary drinks (soft drinks (Coca-Cola, Sprite, Fanta, flavoured waters, ice tea etc) and foods with added sugar (flavoured yoghurts, ice-cream, donuts, ready-made sauces)
sweet and savoury snacks (cakes, cookies, chips)
ultra-processed foods
processed meats (viennas, hams, sausages, salami etc)
frequent fast-food consumption (burgers, pizza, fries etc)

Eating small, regular meals may also help reduce nausea and support adequate nutrient intake.

Are These Medications a Long-Term Treatment?

Many pharmaceutical manufacturers suggest that GLP-1 medications are designed to be used long-term (potentially lifelong treatment) to maintain weight loss.

However, in practice, many people stop treatment within 1–2 years, often due to cost, side effects, or other factors.

Weight regain can occur if good nutrition and lifestyle changes are not maintained.

Because long-term data are still developing, treatment decisions should always be made carefully and under medical supervision.

Who Should Not Use These Medications?

GLP-1 and GLP-1/GIP drugs are not suitable for everyone.

Absolute contraindications may include:

personal or family history of medullary thyroid cancer
multiple endocrine neoplasia syndrome type 2 (MEN-2)
severe gastrointestinal diseases such as gastroparesis
known allergy to the medication

Additional caution may be needed in people with:

history of pancreatitis
gallbladder disease
inflammatory bowel disease
diabetic retinopathy
pregnancy or breastfeeding
certain eating disorders
unstable mental health conditions

For these reasons, any decision to start weight-loss medication should be made in consultation with a qualified medical specialist.

A Holistic Approach to Weight Management

GLP-1 and GIP medications represent an important advancement in the treatment of obesity and metabolic disease.

For many people they can lead to meaningful health improvements.

However, the most effective long-term approach usually combines:

appropriate medical treatment
evidence-based nutrition guidance
physical activity
behavioural and lifestyle support

In other words, sustainable health changes rarely come from a single solution—they come from a comprehensive approach that supports the whole person.

While medications can amplify these hormonal signals, supporting the body’s natural appetite-regulation systems through healthy nutrition and lifestyle remains an important foundation for metabolic health.

Nutrition Support

If you are severely overweight, considering weight-loss medications, or living with chronic health conditions, it is usually recommended to seek guidance from a registered dietitian or nutritional therapist who can provide specialised nutrition care.

If you are slightly overweight and do not have chronic health conditions, but would like support improving your nutrition and lifestyle to support healthy weight management and reduce the risk of conditions such as diabetes or high blood pressure, working with a qualified nutrition counsellor can help ensure your diet supports both health and long-term wellbeing. You can contact me to book a consultation at info@katrinpeo.com.