February 20, 2026
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February 20, 2026

The 5 Biggest Diet Mistakes That Secretly Shorten Your Lifespan

Health and Wellness
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Reviewed By:
Dr Michael Williams
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The 5 Biggest Diet Mistakes That Secretly Shorten Your Lifespan

Contents

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When it comes to longevity, what you eat matters, but it’s not always obvious where we’re going wrong. Some common diet habits may seem harmless or even healthy, but could be silently undermining your long-term health. In this article, we explore five of the most overlooked dietary mistakes that may be reducing your lifespan, and offer evidence-based tips to help you make smarter, more life-extending food choices.

What we eat shapes far more than our weight. Our diet influences our energy, mood, disease risk, and how long we live. With so much nutritional advice, many of us have habits that may be doing more harm than good.  

1. Overeating “Healthy” Ultra-Processed Foods

Processed foods are not inherently bad. For example, our milk is pasteurised to kill bacteria, vegetables, nuts, and seeds are pressed to make oils, and food is preserved in the tinning process1. 

Ultra-processed foods often have more calories, salt, sugar, and fat, and make up around 50 per cent of calories consumed by adults in the UK1,2. Common examples of ultra-processed foods include2:

  • Ham, bacon, and sausages
  • Mass-produced bread
  • Breakfast cereals
  • Crisps 
  • Biscuits
  • Ice cream 
  • Fruit-flavoured yogurts
  • Carbonated drinks

When ‘low-fat’ or ‘plant-based’ isn’t always healthy

Some ultra-processed foods can fit within a healthy diet, such as pre-sliced wholemeal bread, baked beans, or high-fibre breakfast cereals. 

However, many ultra-processed foods that are marketed as ”healthy” are often high in sugar, salt, and refined fats and low in fibre and micronutrients. Relying on them too much can make it harder to meet your nutritional needs. 

These “healthier” foods include:

  • Protein bars
  • Meat alternatives
  • Healthier ready meals
  • Sweetened yogurts  

These often contain additives such as sweeteners, flavourings, and stabilisers that offer little nutritional benefit, making them less wholesome than their labels suggest. 

Why ultra-processed foods matter for longevity

Though not necessarily dangerous, ultra-processed foods are not vital for a healthy life. Most people would likely benefit from enjoying them in small quantities less often. 

Some studies have linked ultra-processed foods to an increased risk of3:

  • Bowel cancer4
  • Type 2 diabetes2
  • Heart disease2
  • Stroke2
  • Chronic inflammation1

A study from the University of Michigan claims that eating a beef hot dog on a bun, which is one of the most highly processed foods there is, can take up to 36 minutes off of a healthy human lifespan5. This highlights how even occasional ultra-processed choices can accumulate over time, chipping away at longevity.

Choosing whole foods can help us reduce the amount of ultra-processed foods. Checking the ingredients list and choosing options with fewer, more recognisable ingredients can help you spot when a ‘health’ product is more marketing than substance.

2. Not Eating Enough Fibre

Dietary fibre comes from plants and is not digestible by humans. It helps prevent constipation, maintain blood sugar, lower our cholesterol, and help us feel fuller for longer. 

The underestimated nutrient

The NHS recommends that adults eat 30g of fibre every day, but in reality, the average adult eats less than 20g6. 

Examples of high fibre foods include:

  • Beans and pulses (e.g., lentils, chickpeas)
  • Vegetables (e.g, broccoli, brussels sprouts)
  • Fruits (e.g., raspberries, pears with skin)
  • Grains and seeds (e.g, oats, chia seeds)

Lifespan and fibre: the connection 

The research shows that those who eat high fibre diets have a lower risk of several diseases6:

  • Heart disease and stroke: around 15-30 per cent risk reduction with every extra 10g of daily fibre7.
  • Bowel cancer: up to 20 per cent lower risk with each extra 10g of dietary fibre8. 
  • Type 2 diabetes: around 15-30 per cent reduced risk by improving insulin sensitivity and blood sugar control9.

By increasing the volume of plants in your diet, your fibre consumption will increase naturally, bringing many health benefits. Additional ways to supplement fibre are by choosing6:

  • Higher fibre breakfast cereal
  • Wholemeal over white bread
  • Keeping the skins on fruits and vegetables
  • Snacking on fresh or dried fruit rather than an ultra-processed alternative. 

In animal studies, high fibre diets help increase longevity10. Some human studies have found that high fibre diets could slow the ageing of cells and ultimately could increase lifespan11. Although more research is needed. 

3. Excess Sugar Intake – Even When You Think You’re Eating “Well” 

Not all sugar is bad. Natural sugars, like those found in fruit, come with fibre, which can slow down absorption and prevent blood sugars from spiking12. Added refined sugars, like modified corn syrup, spike blood sugar fast, contributing to inflammation and diseases over time13. 

Where sugar hides

Sugar lurks in unlikely places, often in surprising quantities, like cereal, smoothies, and many “low-fat” products that are marketed as healthy14. For example, a typical protein bar can contain over 20g of added sugar, which is more than some chocolate bars15.

Over time, these sugar spikes can contribute to cravings and can quietly harm health12,13. 

How sugar accelerates ageing

Excess added sugar fuels insulin resistance, chronic inflammation, and weight gain, and can contribute to the stiffening of blood vessels, which in turn increases the risk of heart disease16,17. 

Over time, uncontrolled blood sugar can lead to metabolic diseases like diabetes and fatty liver disease, while speeding up cellular aging, all of which shorten lifespan18.

Swapping sugary “health” foods for wholesome options helps to break the cycle of craving and eating refined sugar, and protects longevity. This does not necessarily mean cutting out all refined sugar. Your favourite snacks can still be enjoyed, just less often and in smaller portions19. 

4. Skipping Meals or Extreme Dieting

Fad diets are short-term, often highly restrictive diets that promise quick results. Unfortunately, they are unsustainable. Fad diets often trigger a cycle of yo-yo dieting in which people gain and lose weight, which can lead to overall weight gain and health issues20. 

The risks of under-eating or yo-yo dieting

Surprisingly, studies have shown that people who regularly diet actually tend to gain more weight over time21.  

Severe restrictions in your diet can lead to:

  • Nutrient deficiencies: missing key vitamins and minerals can cause fatigue and weakness22. 
  • Slow metabolism: fewer calories are burned at rest, promoting long-term weight gain22.
  • Muscle loss: up to 6x more muscle is lost with repeated yo-yo dieting23. 
  • Stress hormones, e.g., insulin: worsen blood sugar control and metabolic disease risk22.

These issues affect older adults more, leading to frailty and increased disease risk24.  

A more balanced approach to eating

  • Focus on consistency: small, sustainable changes over time are more beneficial than extreme dieting25. 
  • Variety is key: eating a variety of whole foods nourishes your body best25. 
  • Sustainable diets: protect muscle, insulin sensitivity, and a healthy lifespan25. 

5. Ignoring Personal Health Conditions When Choosing a Diet

No diet works the same for everyone. Ignoring your unique health issues can backfire, turning "healthy" eating harmful.

There’s no one-size-fits-all plan

What works for one person might cause issues for another.  This can be due to different genetics, the medication you are taking, illnesses, or intolerances20,26.

  • Diabetes: Foods with a low glycaemic index (GI) will help manage blood sugar and weight. E.g., lentils, chickpeas, oats, most fruits27. 
  • High cholesterol: Plant sterols can block the absorption of “bad cholesterol”, which reduces the risk of heart and liver disease28. 
  • Food intolerances: Swap trigger foods like lactose (dairy) or gluten (bread/pasta) to avoid pain, bloating, and other gut issues. 

The case for personalised nutrition and proactive health screening

Personalised nutrition beats generic advice by accounting for your body's unique needs.

By using data from blood work, scans, or even genetic testing, you can build a plan that targets what matters most to you. This could be improving energy levels, supporting weight control, or reducing disease risk. 

Being proactive with your diet and health means making intentional daily choices that strengthen your long‑term wellbeing.

Conclusion

Poor dietary habits, like relying on ultra‑processed foods, eating high‑sugar “health” products, skimping on fibre, following fad diets, or ignoring your body’s needs, can drain your energy, increase disease risk, and shorten your lifespan.

Small, sustainable changes make a big difference over time. Simple swaps, such as adding fibre to your breakfast or choosing fruit instead of packaged snack bars, can meaningfully improve your long‑term health. 

Pairing these habits with regular check‑ups, such as an Ezra multi‑organ MRI scan, can screen for early indicators of disease, giving you valuable insights to guide smarter lifestyle and dietary choices.

Understand your risk for cancer with our 5 minute quiz.

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References

1. NHS. Processed foods. nhs.uk. February 23, 2022. Accessed February 17, 2026. https://www.nhs.uk/live-well/eat-well/how-to-eat-a-balanced-diet/what-are-processed-foods/ 

2. British Heart Foundation. Ultra-processed foods: how bad are they for your health? British Heart Foundation. December 18, 2025. Accessed February 17, 2026. https://www.bhf.org.uk/informationsupport/heart-matters-magazine/news/behind-the-headlines/ultra-processed-foods 

3. Elizabeth L, Machado P, Zinöcker M, Baker P, Lawrence M. Ultra-Processed Foods and Health Outcomes: A Narrative Review. Nutrients. 2020;12(7):1955. doi:10.3390/nu12071955 

4. Wedekind S. Are ultra-processed foods linked to cancer? Cancer Research UK - Cancer News. April 18, 2024. Accessed February 17, 2026. https://news.cancerresearchuk.org/2024/04/18/are-ultra-processed-foods-linked-to-cancer/ 

5. Stylianou KS, Fulgoni VL, Jolliet O. Small targeted dietary changes can yield substantial gains for human health and the environment. Nat Food. 2021;2(8):616-627. doi:10.1038/s43016-021-00343-4 

6. NHS. How to get more fibre into your diet. nhs.uk. February 23, 2022. Accessed February 17, 2026. https://www.nhs.uk/live-well/eat-well/digestive-health/how-to-get-more-fibre-into-your-diet/ 

7. Barber TM, Kabisch S, Pfeiffer AFH, Weickert MO. The Health Benefits of Dietary Fibre. Nutrients. 2020;12(10):3209. doi:10.3390/nu12103209 

8. Alahmari LA. Dietary fiber influence on overall health, with an emphasis on CVD, diabetes, obesity, colon cancer, and inflammation. Front Nutr. 2024;11:1510564. doi:10.3389/fnut.2024.1510564 

9. Daley SF, Shreenath AP. The Role of Dietary Fiber in Health Promotion and Disease Prevention: A Practical Guide for Clinicians. In: StatPearls. StatPearls Publishing; 2025. Accessed February 17, 2026. http://www.ncbi.nlm.nih.gov/books/NBK559033/ 

10. Hu F, Yu L, Tu X, et al. A high-fiber diet mimics aging-related signatures of caloric restriction in mammals. Nat Commun. 2025;16(1):5917. doi:10.1038/s41467-025-61046-z 

11. Tucker LA. Dietary Fiber and Telomere Length in 5674 U.S. Adults: An NHANES Study of Biological Aging. Nutrients. 2018;10(4):400. doi:10.3390/nu10040400 

12. NHS. Sugar: the facts. nhs.uk. March 3, 2022. Accessed February 17, 2026. https://www.nhs.uk/live-well/eat-well/food-types/how-does-sugar-in-our-diet-affect-our-health/ 

13. British Heart Foundation. Anti-inflammatory diet: what you need to know. British Heart Foundation. December 1, 2023. Accessed February 17, 2026. https://www.bhf.org.uk/informationsupport/heart-matters-magazine/nutrition/anti-inflammatory-diet 

14. NHS. How to cut down on sugar in your diet. nhs.uk. February 23, 2022. Accessed February 17, 2026. https://www.nhs.uk/live-well/eat-well/how-to-eat-a-balanced-diet/how-to-cut-down-on-sugar-in-your-diet/ 

15. Action on sugar. Snack Bars Report - Action on Sugar. Accessed February 17, 2026. https://www.actiononsugar.org/surveys/2025/snack-bars-report/ 

16. British Heart Foundation. Preventing arteries becoming hardened in diabetes. British Heart Foundation. Accessed February 17, 2026. https://www.bhf.org.uk/research-projects/investigating-the-role-of-rankl-signalling-and-glycation-in-vascular-calcification-and-the-potential-for-anticalcification-strategies 

17. Chen X, Tao L, Wang Y. Association of dietary fiber intake with all-cause and cardiovascular mortality in diabetes and prediabetes. Diabetol Metab Syndr. 2025;17:231. doi:10.1186/s13098-025-01810-9 

18. Tseng TS, Lin WT, Ting PS, et al. Sugar-Sweetened Beverages and Artificially Sweetened Beverages Consumption and the Risk of Nonalcoholic Fatty Liver (NAFLD) and Nonalcoholic Steatohepatitis (NASH). Nutrients. 2023;15(18):3997. doi:10.3390/nu15183997 

19. NHS. Healthier food swaps - Food facts - Healthier Families. nhs.uk. December 13, 2021. Accessed February 17, 2026. https://www.nhs.uk/healthier-families/food-facts/healthier-food-swaps/ 

20. Tahreem A, Rakha A, Rabail R, et al. Fad Diets: Facts and Fiction. Front Nutr. 2022;9:960922. doi:10.3389/fnut.2022.960922 

21. Lowe MR, Doshi SD, Katterman SN, Feig EH. Dieting and restrained eating as prospective predictors of weight gain. Front Psychol. 2013;4:577. doi:10.3389/fpsyg.2013.00577 

22. Most J, Redman LM. Impact of calorie restriction on energy metabolism in humans. Exp Gerontol. 2020;133:110875. doi:10.1016/j.exger.2020.110875 

23. Zamboni M, Giani A, Fantin F, Rossi AP, Mazzali G, Zoico E. Weight cycling and its effects on muscle mass, sarcopenia and sarcopenic obesity. Rev Endocr Metab Disord. 2025;26(5):767-783. doi:10.1007/s11154-025-09963-8 

24. Porter Starr KN, McDonald SR, Bales CW. Nutritional Vulnerability in Older Adults: A Continuum of Concerns. Curr Nutr Rep. 2015;4(2):176-184. doi:10.1007/s13668-015-0118-6 

25. Cena H, Calder PC. Defining a Healthy Diet: Evidence for the Role of Contemporary Dietary Patterns in Health and Disease. Nutrients. 2020;12(2):334. doi:10.3390/nu12020334 

26. de Ridder D, Adriaanse M, Evers C, Verhoeven A. Who diets? Most people and especially when they worry about food. Appetite. 2014;80:103-108. doi:10.1016/j.appet.2014.05.011 

27. Diabetes UK. Glycaemic index and diabetes. Diabetes UK. Accessed February 17, 2026. https://www.diabetes.org.uk/living-with-diabetes/eating/carbohydrates-and-diabetes/glycaemic-index-and-diabetes 

28. Malhotra A, Shafiq N, Arora A, Singh M, Kumar R, Malhotra S. Dietary interventions (plant sterols, stanols, omega‐3 fatty acids, soy protein and dietary fibers) for familial hypercholesterolaemia - Malhotra, A - 2014 | Cochrane Library. Accessed February 17, 2026. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD001918.pub3/full