Author: Cathy Robinson, BScDipNutMed

Obesity and Cancer Risk

Obesity and Cancer Risk

Table of Contents:

New findings show having excess weight has overtaken smoking as the cause of several cancers.

We always take an evidence-based approach - in this article we’ll take a closer look at the figures and examine why obesity is linked to cancer.


Obesity Causes More Cancer Than Smoking

Being obese or overweight is a causative factor in almost two thousand more cases of bowel cancer each year than smoking, according to figures released by Cancer Research UK (1).

The report also named obesity as causing 1400 more cases of kidney cancer than smoking, 460 more cases of ovarian cancer and 180 more cases of liver cancer.

In fact obesity is recognised as a significant factor in 13 different types of cancer, including cancers of the womb, oesophagus, pancreas, stomach, gallbladder and thyroid (2).

Additionally, obesity may cause some types of cancers to be more aggressive.

Although smoking remains the biggest cause of cancer overall, with 15% all cancer deaths in 2015 attributable to smoking, obesity and overweight accounted for 6% of all cancer deaths in the same year.

The gap between the relative contribution of smoking and obesity to cancer is much narrower for females than for males, because obesity has a greater impact on female sex hormone related cancers.

All this adds up to more than 1 in 20 cancers in the UK being attributable to obesity.

The risk is higher the more overweight a person is and the longer they remain obese.

Cancer Research UK estimate that overweight and obesity, if they continue increasing at their present rate, could overtake smoking as the leading preventable cause of cancer in women by 2035.


How Widespread are Obesity and Smoking?

In the UK, smoking rates have fallen in recent years.

14.9% of adults were classed as smokers in 2017, down from 19.8% in 2011, but alongside this obesity rates have risen and there are now twice as many obese people than smokers (3).

Across the whole of the UK, around 14.9 million adults are classified as obese, which represents around 29% of the UK population.

Particularly worrying is the rise in childhood obesity, with one in five children obese before they start primary school.

This rises to one third by the time they leave primary school (4).

If obesity is implicated in 13 types of cancer, it’s reasonable to assume the conditions in the body created by obesity which allow those cancers to grow would also encourage other types of cancers and chronic illness.


A Campaign to Reduce Obesity

The findings have brought about a poster campaign funded by Cancer Research UK which show giant cigarette packets bearing the strapline ‘Obesity is a cause of cancer too’.

The idea behind the campaign is not simply to change public behaviour but also to alter public policy, such as restricting junk food advertisements.

The campaign has raised criticisms that it creates a blame culture.

Concerns have been raised that it may discourage people from seeking help to lose weight owing to embarrassment, or even lead to overweight women avoiding attending breast and cervical cancer screenings.

Other objections have centred on the issue that statistics may be muddled owing to the increased risk of cancer for lower socio-economic groups.


Why Does Obesity Cause Cancer?

The link between obesity and cancer is not completely clear, but it’s believed to be largely due to visceral fat – the kind which sits around the body’s organs.

Fat cells are not passive, they release chemical messages which communicate instructions to other cells, particularly in connection with cell growth and reproduction.

This type of fat also increases oxidative stress and stimulates the immune system to become hyperactive (5).

Fat cells also release pro-inflammatory signalling chemicals.

Short term inflammation is the body’s natural protective response to injury, however when it becomes ongoing it can cause all sorts of problems.

For example, it can prevent the body from responding to the message of insulin - a situation called insulin resistance.

This leads to increased release of insulin and an upsurge in cell division.

When cells divide uncontrollably the risk of cancer increases.

Increased insulin levels can also encourage higher oestrogen levels, which would explain the link between obesity and oestrogen-dependent cancers.

Fat cells also directly produce oestrogen.

Elevated oestrogen again encourages cells to divide.

Finally sugar consumption has been found in research to stimulate the growth of cancer cells (6).

It’s worth bearing in mind that it is possible to have visceral fat without being obese or even overweight, so we still don’t completely understand the link between obesity and cancer risk.


How Can I Maintain a Healthy Weight?

Simple steps you can take today to help maintain your weight include:

  • Stay active. The NHS recommends at least 150 minutes of moderate exercise, such as cycling or brisk walking, or 75 minutes of vigorous exercise, such as running or tennis, per week.
  • Eat mainly plant-based foods, choosing a broad range of colours.
  • Reduce or avoid alcohol.
  • Sleep at least seven hours per night, preferably more, as insufficient sleep is linked to being overweight.



If you want to live a healthy life, it’s important to maintain a healthy weight.

For many people this is not as easy as it sounds.

If you have tried losing weight using the above strategies without success, your personal metabolism or hormonal picture may be predisposing you to retaining excess weight.

Working with an experienced Amchara Health Practitioner can help remove obstacles to attaining your optimal weight.

Start your journey with a complimentary initial 360° health consultation today.

We believe sharing knowledge and experience is an important part of achieving optimal health and would love to hear your views and experiences.

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