Why Your Body Needs Dietary Fat: Functions, Sources, Evidence

Educational content - not professional advice. The information in this article is provided for general educational purposes only and does not constitute medical, nutritional, fitness, or professional advice. It is not a substitute for advice from a qualified healthcare professional. Always consult your GP or relevant specialist before starting any new exercise programme, diet, or health-related activity. DT Fitness London accepts no liability for decisions made based on the content of this article. See our Health & Exercise Disclaimer and Nutrition Disclaimer.

Dietary fat is essential. The fat-free era of the 1980s and 1990s left long shadows that the science has long since corrected. The body requires fat for hormone production, brain structure, vitamin absorption, and cell membrane integrity. The story is not about avoiding fat. It is about choosing the right ones and getting enough.

What fat does

  • Hormones. Cholesterol is the precursor for testosterone, oestrogen, and cortisol. Very low fat intakes blunt sex hormone production.
  • Brain. The brain is around 60 percent fat by dry weight. Omega-3 EPA and DHA support cell membrane fluidity and signalling.
  • Vitamins. A, D, E, and K are fat soluble. Without dietary fat, absorption drops.
  • Satiety. Fat slows gastric emptying. Meals with adequate fat hold hunger longer than fat-free ones at the same calorie load.

The three categories that matter

Unsaturated (mono and poly)
Olive oil, rapeseed oil, avocado, nuts, seeds, fatty fish. Linked to lower CVD risk in trials and large cohorts. Fish twice a week or 1 to 2 g EPA+DHA if you do not eat fish.
Saturated
Butter, fatty cuts of meat, full-fat dairy, coconut oil. UK SACN recommends under 10 percent of daily energy. Not the demon some advice still paints, but still worth limiting relative to unsaturated sources.
Industrial trans (partial hydrogenated)
Worst-evidence category. WHO recommends global elimination from the food supply. Avoid where flagged on labels (UK now restricts industrial trans fats to small amounts).

How much fat to eat

A practical adult range sits at 25 to 35 percent of daily energy from total fat, with the majority coming from unsaturated sources. For an 1,800 kcal day, that is 50 to 70 g total fat. Athletes and very active adults sit at the higher end. People with familial hypercholesterolaemia need clinician-specific guidance.

Work with DT Fitness London

For a nutrition plan that gets fats, protein and carbs right for your goals, book a consultation at www.dushyantatomar.com.

Dushyanta Tomar, MSc Applied Sports and Exercise Physiology, CIMSPA Accredited Personal Trainer.

Sources

  1. SACN. Saturated fats and health. UK Government. gov.uk
  2. Estruch R, Ros E, Salas-Salvado J, et al. Primary Prevention of Cardiovascular Disease with a Mediterranean Diet Supplemented with Extra-Virgin Olive Oil or Nuts. N Engl J Med. 2018, vol 378, e34.
  3. World Health Organization. REPLACE: trans fat elimination. who.int
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