Fat Is Not Optional
Dietary fat provides essential fatty acids the body cannot make, carries the fat-soluble vitamins A, D, E and K, and is the substrate for steroid hormone production. Intakes below about 20% of calories impair these functions, which is why very low-fat diets fail people in ways low-carbohydrate diets do not.
At 9 calories a gram, fat is also the most energy-dense macronutrient — more than double protein or carbohydrate.
Fat Intake Chart
For a 2,700-calorie intake:
| Fat share of calories | Total fat | Saturated limit (10%) | Suits |
|---|---|---|---|
| 20% | 60 g | 30 g | Low fat, higher carbohydrate |
| 25% | 75 g | 30 g | Balanced, endurance training |
| 30% | 90 g | 30 g | The dietary guidelines midpoint |
| 35% | 105 g | 30 g | Mediterranean pattern |
| 45% | 135 g | 30 g | Low carbohydrate |
| 70% | 210 g | 30 g | Ketogenic |
The saturated fat limit does not move with the total — it stays at 10% of calories. Higher-fat diets therefore require proportionally more of that fat to come from unsaturated sources.
The Four Types
- Monounsaturated — olive oil, avocado, most nuts. The best-supported fat for cardiovascular health.
- Polyunsaturated — oily fish, walnuts, flax, sunflower and soybean oil. Contains the two essential fatty acids, linoleic acid and alpha-linolenic acid.
- Saturated — meat, butter, cheese, coconut and palm oil. Raises LDL cholesterol; both the WHO and the AHA recommend capping it near 10% of calories, or 6% for people lowering cholesterol.
- Trans — industrially produced partially hydrogenated oils. Banned or heavily restricted in most countries, with no safe level.
Omega-3 and Omega-6
Both are essential and both are polyunsaturated. Western diets typically supply omega-6 in abundance from seed oils and omega-3 in short supply. The adequate intake for ALA is 1.6 g a day for men and 1.1 g for women; for EPA and DHA, two portions of oily fish a week is the common recommendation. The evidence for supplementing beyond that is mixed.
The Saturated Fat Debate
Saturated fat reliably raises LDL cholesterol. Whether reducing it reduces cardiovascular events depends heavily on what replaces it: replacing it with polyunsaturated fat lowers risk, replacing it with refined carbohydrate does not. This is why current guidelines emphasise the replacement rather than the reduction alone.
Frequently Asked Questions
Is dietary fat the same as body fat?
No. Any excess calories are stored as body fat, whatever the source. Dietary fat is simply the most calorie-dense and therefore the easiest to over-consume.
Which cooking oil is best?
Olive oil for most cooking and dressings. For high-heat cooking, avocado or refined olive oil have higher smoke points. Whether cold-pressed extra virgin oil is worth its premium for cooking rather than dressing is debatable.
Do I need to avoid dietary cholesterol?
For most people, no. Dietary cholesterol has a modest effect on blood cholesterol in the majority of the population, which is why the specific 300 mg limit was removed from the US guidelines in 2015. Saturated fat intake matters considerably more.