The Low-Fat Era Was a Mistake
In the 1980s and 1990s, dietary fat was public enemy number one. Governments told people to cut fat, food companies replaced it with sugar, and obesity rates climbed steadily. We now know that dietary fat is not the villain — and that cutting it too low can actively harm your health.
What Fat Does in Your Body
Builds every cell membrane — Every cell in your body is surrounded by a phospholipid bilayer made of fat. The quality of the fat you eat directly affects the flexibility and function of your cell membranes.
Produces hormones — Sex hormones (testosterone, estrogen, progesterone) and steroid hormones are synthesized from cholesterol, a type of fat. Eating too little fat suppresses hormone production, which can reduce energy, libido, mood, and muscle-building capacity.
Absorbs fat-soluble vitamins — Vitamins A, D, E, and K require dietary fat for absorption. A fat-free salad with carrots (vitamin A) absorbs a fraction of its nutrients compared to one with olive oil. Chronic fat restriction leads to deficiencies in these essential vitamins.
Fuels your brain — Your brain is about 60% fat by dry weight. DHA, an omega-3 fatty acid, is a structural component of brain cell membranes and is critical for cognitive function, memory, and mood regulation.
Provides long-lasting energy — At 9 calories per gram, fat is the most energy-dense macronutrient. It provides slow-burning fuel for low-intensity activity and extended exercise.
Supports inflammation control — Omega-3 fatty acids (from fatty fish, flaxseed, walnuts) have anti-inflammatory properties. The balance between omega-6 and omega-3 intake significantly influences chronic inflammation in your body.
Types of Fat — What to Prioritize
Unsaturated fats (prioritize):
- Monounsaturated: olive oil, avocado, almonds, cashews — heart-protective, anti-inflammatory
- Polyunsaturated (omega-3): salmon, mackerel, sardines, walnuts, chia seeds — brain health, reduces inflammation
- Polyunsaturated (omega-6): sunflower oil, corn oil — needed but most people already get too much
Saturated fat (moderate):
- Butter, coconut oil, red meat, full-fat dairy — not as harmful as once believed, but excessive intake is still linked to elevated LDL cholesterol in some people
Trans fats (avoid):
- Partially hydrogenated oils, found in some packaged snacks, margarine — the only type of fat consistently shown to increase heart disease risk with no compensating benefit
How Much Fat Do You Need?
Most nutrition guidelines recommend 20–35% of total calories from fat. For a 2,000-calorie diet, that's 44–78g of fat per day.
Going below 20% of calories from fat for extended periods suppresses hormones, impairs vitamin absorption, and reduces the palatability of food — making your diet harder to sustain.
Signs You Might Be Eating Too Little Fat
- Dry skin and hair
- Hormone imbalances (low libido, irregular cycles)
- Difficulty absorbing vitamins (despite good intake)
- Poor cognitive function or brain fog
- Feeling unsatisfied after eating
The Bottom Line
Fat doesn't make you fat. Excess calories do. Dietary fat is essential for hormones, brain health, vitamin absorption, and cell function. Prioritize unsaturated fats, eat saturated fat in moderation, and eliminate trans fats entirely.