Are you missing key nutrients? 6 vitamin deficiency signs from GLP-1 side effects
From fatigue and muscle weakness to changes in mood and skin, there are several potential signs that may indicate a vitamin deficiency while on weight loss injections.
If you’re among the estimated 2.4 million people in the UK using weight loss injections, it’s worth looking beyond the scales. While these medications can be effective, the side effects of GLP-1 treatments can sometimes come with unintended nutritional gaps.
Like most medications, GLP-1s bring a range of physical changes, as well as weight loss. From nausea to fatigue, many of these are expected. But one of the more overlooked side effects of GLP-1 use is a gradual drop in essential nutrient intake, often caused by eating less overall.
So, how can you tell if your body is missing something important? Here are six key signs to watch for and how to easily incorporate key vitamins and nutrients into your diet.
What are the common side effects of weight loss jabs?
Before looking at signs of deficiencies, it helps to understand what’s happening in your body. If you’ve ever wondered what the side effects of the weight loss jab are, most stem from how GLP-1 medications interact with appetite, digestion and blood sugar regulation.
Nausea
Medications such as semaglutide, best known as Ozempic or Wegovy, mimic the GLP-1 hormone that controls appetite and digestion. One of the most common side effects of GLP-1 use is nausea, with studies suggesting 40 to 81 percent of users experience it.
This happens because food stays in the stomach for longer, creating a prolonged feeling of fullness. At the same time, receptors in the brain linked to nausea are activated, which can heighten the sensation.
Digestive issues
Because digestion slows down, symptoms like constipation, diarrhoea, indigestion, bloating and abdominal discomfort can follow. For most people, these settle over time as the body adjusts, but persistent issues should always be discussed with a GP.
Fatigue
Many people ask, can GLP-1 cause fatigue? The short answer is yes. Feeling unusually tired is one of the more common side effects of GLP-1 medications.
This is often linked to a lower calorie intake, changes in blood sugar levels and the overall adjustment your body is making. If you’ve found yourself wondering why your GLP-1 makes you tired, it’s usually a combination of eating less and your metabolism adapting to that shift.
Headaches
Headaches are also reported, affecting around 4 to 14 percent of users. These are often tied to dehydration, blood sugar fluctuations or gastrointestinal side effects like vomiting, particularly in the early stages.
Explore our previous blog to discover all the common challenges and side effects of weight loss injections.
What are the vitamin deficiency signs to look out for?
A reduced appetite might feel like a benefit, but it can also mean fewer nutrients are being consumed overall. Over time, this can lead to deficiencies that are easy to miss, especially when symptoms overlap with the typical side effects of GLP-1 use.
If you’re noticing ongoing symptoms, it’s worth considering whether your diet is providing everything your body needs.
Constant tiredness
Ongoing fatigue, weakness or low energy levels could point to deficiencies in nutrients such as vitamin B12, vitamin D or iron.
If you’re wondering if your Mounjaro fatigue will go away, the answer can depend on what action you take. For some, the fatigue improves as the body adjusts. For others, it may be linked to nutritional gaps that need addressing.
Hair, skin and nail changes
Changes in appearance can often be one of the first visible signs. Brittle nails, thinning hair or dull skin may indicate a lack of protein, iron, zinc or key vitamins such as C and D.
In some cases, iron deficiency can also lead to pale skin or spoon-shaped nails.
Muscle weakness
If your muscles feel weaker than usual, it may be more than just weight loss. Low levels of vitamin D, calcium, iron or magnesium can all affect muscle function.
Combined with reduced muscle mass during weight loss, this can become more noticeable, particularly during life stages like menopause.
Low mood
Mood changes are another sign that’s easy to overlook. Low levels of vitamin D or magnesium can impact how you feel day to day, as both play a role in supporting brain function and emotional balance. Some studies have shown significant increases in depression, anxiety, psychiatric disorders and suicidal behaviour in users versus non-users of these drugs.
Heart changes
Certain deficiencies, including magnesium, potassium and iron, can affect heart health. Symptoms such as palpitations, shortness of breath or an irregular heartbeat should never be ignored.
If you experience chest pain, fainting or sudden discomfort that spreads to other areas of the body, seek medical attention immediately.
Frequent illnesses
If you notice you are getting sick with colds, flu or other bugs more frequently, it could indicate that you are not getting enough vitamin D, C or A.
While many people focus on the more obvious side effects of GLP-1 medications, nutritional deficiencies can quietly develop in the background.
The good news is that they’re manageable with the right approach. Paying attention to what your body is telling you and ensuring you’re getting the nutrients you need can make all the difference, helping you stay healthy while still working towards your weight loss goals.
How to maintain a balanced diet whilst on weight loss injections
Weight loss injections can quieten your appetite, but they can also quieten your nutrient intake. Once you understand that trade-off, the focus shifts from simply eating less to eating smarter.
This is where things often get tricky. Smaller portions can mean missed nutrients, while planning what to eat on GLP-1s every day can feel like hard work when you’re not especially hungry. Add the confusion around supplements and it’s easy to lose sight of what your body actually needs.
Our approach keeps things simple. Instead of overthinking every meal or stocking up on multiple vitamins, our low-calorie shakes, snacks and soups are designed to do the heavy lifting for you. They deliver targeted nutrition in portions that feel manageable, even on low appetite days.
Most people incorporate two to three PortionIQ products into their day, depending on what works for them. Here’s how they fit in:
Very Berry Bites
Think of these as a small but powerful reset. With 20g of protein, 21 vitamins and minerals and just 212 calories, they offer a quick, satisfying way to stay nourished without committing to a full meal.
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St. Clements Electrolytes
Hydration can take a big hit when calories are substantially reduced. Each sachet helps replenish electrolytes while delivering 25 essential vitamins and minerals, supporting energy levels and overall balance.
Protein-Packed Vegetable Soup
Comforting, filling and nutrient-dense, this soup delivers 20g of protein, 26 vitamins and minerals and just 246 calories. It’s an easy way to add something warm and substantial to your day without overdoing it.
Mixed Berry Shake
When you need something quick, this shake ticks every box. Packed with protein, fibre and 26 essential vitamins and minerals and just 205 calories, it supports digestion, energy and immunity in a format that fits seamlessly into your routine.
Ready to rethink your nutrition?
Backed by 40 years of scientific research, these products are built to support you through every stage of your weight loss journey. They take the pressure out of planning, helping you stay consistent, balanced and properly nourished while using weight loss injections.
Because losing weight shouldn’t mean missing out on what your body needs.