Vitamins & Supplements for Weight Loss: B12, Omega 3 & Magnesium

By Alok 29th October 2021 Category: Advice

Why are vitamins important?

The relevance of macronutrients in metabolism, body composition and weight loss or gain is a well understood and heavily investigated area of health and medicine. However, the impact of micronutrients on the processes that affect body composition and weight is often deprived of attention or considered unimportant.

Micronutrients, or vitamins and minerals, form an essential component of a healthy, balanced diet that on the whole cannot be produced by the body and must be obtained from dietary sources. Inadequate intake of micronutrients can have a serious impact on health and wellbeing. Vitamins and minerals play a crucial role in how the body controls metabolism, blood pressure, the levels of fats in the blood and even the ageing process.

Many investigations have observed a direct link between obesity and micronutrient deficiencies. Interestingly, excess body weight has been found to interfere with the way the body processes micronutrients which can lead to deficiency. This, in turn, can give rise to problems with the way glucose is processed and can cause resistance to insulin (one of the hormones responsible for controlling the amount of glucose in the blood).

A large study of over 15,000 overweight or obese participants published in The Journal of Alternative and Complementary Medicine found that people who took multivitamins and other micronutrients gained significantly less weight than people who did not. It has also been found in a study published in the International Journal of Obesity that the use of multivitamin and mineral supplements is linked with lower body weight, body mass index (BMI) and waist circumference.

Here we will explore three micronutrients that are incorporated into the Mediweight programme: Vitamin B12, Omega 3 and Magnesium. We will look into the function, benefits and sources of each micronutrient, and also at the impacts of deficiency.

Vitamin B12

Vitamin B12 is a vitamin derived from animal products such as liver, beef, lamb, chicken, eggs and dairy. B12 is involved in the generation of energy in cells, and in the production of certain important biological molecules such as DNA. B12 is absorbed from ingested food in a part of the small intestine in a complex process where it is transported into the blood and around the body.

B12 is in fact stored in excess in the liver, however if the diet is deficient of B12 or there is problem with absorption in the gut, stores may become depleted giving rise to B12 deficiency. Symptoms of deficiency commonly include fatigue, pale looking skin, weakness, changes in digestive habits, loss of appetite and problems with the nervous system and memory.

What is the link between B12 and weight loss?

It has been found that vitamin B12 levels in the blood are lower in obese adults and that low vitamin B12 levels are linked to higher BMI. Whilst the link between vitamin B12 deficiency and obesity is not clear, it has been suggested that low B12 levels can lead to excess fat accumulation. In order to prevent vitamin B12 deficiency and the associated problems, at Mediweight, patient diets are tailored on an individual level to ensure optimal intake of B12 from food sources or supplements if required.

A question that is sometimes asked is, “Can B12 cause weight gain?” For some people, the symptom profile of B12 deficiency can include loss of appetite. In these cases, if the B12 deficiency is returned to normal with supplements or diet alterations, appetite and calorie intake may increase. Naturally, if calorie intake increases without an adjustment to the number of calories burned, weight gain is a likely outcome. However, this explanation makes it clear that it is not the Vitamin B12 that causes weight gain, but rather the increased consumption of food.

Omega 3

Omega 3 fatty acids are a group of unsaturated fatty acids that are named to reflect their chemical structure. The role of these fatty acids is centred around lowering the levels of circulating fat in the body. Omega 3s reduce the activity of enzymes involved in the production of cholesterol and other types of fatty acids. This can lead to reduced blood pressure, reduced inflammation and protection against various cardiovascular diseases.

Oils containing these particular fatty acids can be found in plant-based foods like seeds, nuts, green leafy vegetables and beans, and oily fish.

Interestingly, it is not only omega 3 fatty acids that are important when it comes to interpreting cardiovascular disease risk. Omega 6 fatty acids are a second type that are important here. Humans evolved on a diet containing an equal ratio of omega 3: omega 6 fatty acids. However, modern western diets commonly contain excessive amounts of omega-6 fatty acids and are deficient in omega 3 fatty acids. It is this excess of omega 6 that is linked to increased risk of cardiovascular disease, cancers and autoimmune diseases. Consuming higher quantities of omega 3 fatty acids and reduced quantities of omega 6 fatty acids will reduce this ratio and help in reducing the risk of multiple chronic diseases.

Omega 3 and weight loss

The consumption of omega 3 fatty acids has been shown to be linked to reduced waist circumference but the evidence linking omega 3 and weight loss is inconclusive. However high omega 6: omega 3 ratio is linked to excess body fat and higher cholesterol and increasing consumption of omega 3 fatty acids is a helpful way to reduce this ratio.


Minerals are important components of the diet that are involved in many body processes. Magnesium is the fourth most common mineral in the human body and is crucial for the proper functioning of muscles and nerves, and also in the generation of energy.

In order to ensure optimal consumption of magnesium, it is important to know which foods contain high levels of the mineral. It is also possible to take magnesium supplements dietary intake is not adequate. Foods that contain high levels of magnesium include almonds, bananas, broccoli, cashew nuts, flaxseed, green vegetables, seeds, tofu and whole grains.

Magnesium and weight loss

Magnesium deficiency has been shown to increase inflammation and is linked to obesity. The use of magnesium supplements is even associated with reduced BMI and blood pressure.

If you would like to, you can click here to find out more about how Mediweight can help guide you along your weight-loss journey.

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