by Dr Deborah Lee, Dr Fox Online Pharmacy
63.8% of the UK population are overweight or obese, according to a 2023 government survey. Obesity is also a major problem in children, affecting around 20% of children by the age of 5, and 23% by age 11.
Most people do not immediately equate obesity with being malnourished, but this is indeed the case. Its easy to assume that because a person is well covered, they are getting enough nutrients, but the opposite is true. Research shows that micronutrient (vitamin and minerals) deficiency is more common in those with a raised BMI than in those of the same age and sex who are not obese.
Why should this be?
Why are obese people malnourished?
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Too much calorie-dense food with a low nutrient content
Obesity is often associated with eating processed and ultra-processed foods which are generally high in fat, sugar and salt. In a 2021 study, two groups of non-obese adults followed either an ultra-processed or a healthy diet for 2 weeks and then groups were swapped over. Participants were allowed to eat as much as they liked. The investigators found that those who ate the ultra-processed food, consumed an additional average of 500 calories a day. They also gained around 1 Kg in the 2 weeks while on the ultra-processed diet but lost around 1 Kg on the healthy diet.
Ultra-processed foods are any foods that have been modified to make them taste better or have a longer shelf life. They include cakes, biscuits, pastries, sweets, chocolate, crisps, ice cream, fruit yoghurts, instant foods, sauces, ready meals, chicken nuggets, burgers, hot dogs, pizza, pies, preprepared pasta, soups and desserts.
On average 54% of calories from the UK diet is made up of processed foods. These foods typically have lower nutrient content than unprocessed foods. This could be because the outer casing has been stripped – for example with refined grains. It may be because the food has been heated to high temperatures before cooking or canning/bottling/freezing, destroying much of the nutritional content. Additives are then incorporated such as emulsifiers, flavourings, colourants and preservatives all of which can cause food allergies, irritation to the GI tract, and exacerbate symptoms of irritable bowel syndrome (IBS). Some food additives are believed to be carcinogenic.
Processed foods are typically made with lower-quality ingredients and are cheaper to buy than fresh alternatives. They are often bought in bulk and are seen as a good option for those shopping on a budget or needing to feed a family.
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Making poor dietary choices
Most people do know how to eat healthily – they just don’t or can’t do it. For some, this may be because their lives are so busy and processed food is quick and convenient. But many are tempted by the attractive packaging and clever marketing techniques of convenience foods. Stress and anxiety fuel emotional eating – comfort eating – a time when we crave certain foods, usually fast foods (processed foods) high in fat, carbs and salt. Stress levels in the UK at present are at an all-time high. When we regularly eat these types of foods, we lose our natural appetite for fresh fruit and veg and tend to continue to feed off the unhealthy processed options – it becomes a vicious spiral.
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Living on a low income
Undoubtedly not being able to afford food is a major problem which has worsened in the current cost of living crisis. Wage stagnation and the relentless increase in food prices have put more people than ever into food poverty. Understandably, people would rather eat processed food than go hungry because they can’t afford fresh food alternatives. Food banks have seen unprecedented demand, with many people reportedly living off tea and toast and skipping meals. The soaring cost in energy costs has left many people unable to switch on the oven or the hob.
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Those suffering from disabilities, physical and mental health difficulties
Some people may be confused about what is healthy and what isn’t. Shopping and physically obtaining the food can be difficult for those who are disabled, or live a long way from the shops and have no transport. Fuel, bus and taxi fares are now more expensive, adding to the cost of getting the food home. Poverty is a major cause of stress and anxiety, and quick convenience food can be an easy solution. Those with learning disabilities are known to be at higher risk of malnutrition.
Over 2 million UK residents live with chronic disease, and this is set to increase as the elderly population continues to rise. 54% of people aged 65 and older already have 2 or more chronic diseases – including heart disease, type-2 diabetes and dementia. A strong link has been established between weight gain and obesity and chronic diseases, as well as thirteen different types of cancer.
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Food is less nutritious than it used to be
Nutritionists are concerned that the protein, vitamin and mineral content of fruit and vegetables has been declining in recent years. For example, in one 2022 Australian study, the iron content of sweet potato, cauliflower, green beans, peas and chickpeas had declined by 30% – 50% in the past 20 years. Other studies have had similar findings. This is thought to be because the methods used to irrigate, fertilise and harvest crops now damage the soil, and because of rising levels of CO2 due to climate change.
How does obesity cause malnutrition?
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Obesity causes micronutrient deficiencies
Recent research has identified many micronutrient deficiencies which occur as a result of obesity. A high-fat diet is associated with a lower intake of many vitamins – Vitamins A, C, D, E, B1, B9 and B12.
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Obesity causes long-term damage to the gut-barrier
The gut epithelial cells usually have tight junctions in between them, allowing the passage of nutrients and water, but keeping out toxins and unwanted metabolites. In obesity, these junctions become weakened, and this protective effect is lowered. The process is not completely understood but is closely governed by the type of gut bacteria that are present.
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Obesity disrupts the microbiome
Obese subjects have an increase in lipopolysaccharide (LPS) in their intestines which are produced by gut bacteria. LPS causes chronic gut inflammation and intestinal leakage. The type of gut bacteria present in the GI tract appears to play a crucial role in obesity.
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Obesity alters neurotransmission
Obese people may not get the same appetite and satiety cues when they eat as those of normal weight. It’s well established that obesity is associated with disturbances in the neurotransmission pathways that govern appetite, hunger and satiety. The GABA, 5-HT and acetylcholine pathways are good examples.
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Obesity causes oxidative stress
Obesity causes oxidative stress, and oxidative stress cause obesity.
Oxidative stress is a dangerous metabolic pathway which occurs as a result of oxidation – the process of producing energy – which is taking place all the time in every cell of our bodies. As a result of oxidation, electrically charged particles called reactive oxygen species (ROS) are produced, which have the ability to damage DNA. ROS are thought to underpin the development of many of the chronic diseases we see today – including obesity.
Oxidative stress leads to the deposition of white adipose tissue. It also affects appetite and satiety by disrupting neurotransmission and feedback regarding hunger and satiety. Oxidative stress is linked to higher levels of leptin and leptin resistance. Antioxidants obtained from the diet largely from fruit and vegetables are vital for counteracting oxidative stress, but obese subjects tend to have unhealthy diets lacking in antioxidants.
Final thoughts
Obesity can be a highly distressing condition and has serious medical consequences. The Royal College of Physicians is calling for obesity to be recognised as a disease – not just a lifestyle factor. There should be no shame or stigma in seeing your GP and asking for help. As we have seen in this article, the consequences of obesity are profound, leading to a significant risk of malnutrition and its complications.
- Do you know your BMI? Are you in the obese category?
- If so, what could you do to improve your nutritional health today?