If you’ve ever felt confused about fat, you’re not alone. For decades, the advice was simple: cut fat, lose weight. So why does it feel like that advice never quite worked?
Turns out the story is more complicated than “fat is bad.” Some fats may actually support the goals a lot of people are working toward, including steady energy and a healthier relationship with weight. The key isn’t eating less fat. It’s understanding which fats you’re eating.
Why “Eat More Fat” Isn’t as Strange as It Sounds
Not all fat behaves the same way in the body. Broadly, fats fall into a few categories: saturated, trans, monounsaturated, and polyunsaturated. Trans fats are commonly found in highly processed foods, while saturated fats are found in foods such as butter, cheese, fatty meats, and some tropical oils. Most health organizations recommend limiting both. (1)
Monounsaturated and polyunsaturated fats are a different story. These are the fats found in olive oil, nuts, seeds, and fish, and research suggests that when they replace saturated fat in the diet, they may support healthier cholesterol levels and overall metabolic health. (2) Omega-3 fatty acids, a type of polyunsaturated fat, may also help support a healthy inflammatory response and everyday cellular function. (3)
Where to Actually Find These Fats
You don’t need anything exotic. Some of the most researched sources of healthy fats include:
- Olive oil and avocados (monounsaturated fat)
- Walnuts, flaxseed, and sunflower oil (polyunsaturated fat)
- Salmon, sardines, and mackerel (omega-3s)
- Canola oil and soybean oil (a mix of both)
A lot of people don’t realize how easy it is to swap in these fats without overhauling an entire diet. Cooking with olive oil instead of butter, snacking on walnuts instead of chips, or adding salmon to the weekly rotation are small shifts that add up over time.
If you’re also working on feeling lighter and more comfortable day to day, you can explore additional support for healthy digestion and weight management.
What About Metabolism Slowing Down With Age?
This is where things get interesting. Many people assume metabolism takes a nosedive the moment you hit 40. But one of the largest studies ever done on human energy use, which tracked more than 6,000 people from infancy to age 95, found that metabolism actually stays fairly steady from your twenties all the way through your fifties. The real shift tends to happen closer to age 60. (4)
That doesn’t mean nothing changes in midlife. Muscle mass, activity levels, sleep, and stress all shift with age, and those factors genuinely do affect how the body uses energy. But the “your metabolism is broken at 40” narrative isn’t quite accurate. For many adults, this becomes more noticeable simply because daily habits shift, not because the body suddenly stops working.
The Liver Connection Most People Miss
Here’s something worth knowing: ongoing fatigue and general discomfort may sometimes be associated with underlying liver health, although many people with fatty liver have no noticeable symptoms at all. (5) This doesn’t mean every case of low energy is liver related. But if fatigue and weight struggles seem to show up together over time, it may be worth looking at liver health as part of the bigger picture.
At first glance, that might seem unrelated to what you eat. But since the liver plays a central role in metabolizing fats and regulating lipid metabolism, the type of fat in your diet may matter here too. If you’re interested in supporting your liver as part of this bigger picture, learning more about evidence-based liver support may be a reasonable next step.
The Bottom Line
Fat isn’t the enemy it was once made out to be. The type of fat matters more than the amount, and small, consistent swaps toward monounsaturated and polyunsaturated sources may support metabolic health over time. Combine that understanding with realistic expectations about how metabolism actually changes with age, and a clearer picture starts to form, one that includes how well your liver is keeping up with everything you’re asking your body to do.
Explore Support for Liver Health
Sources
- Harvard Health Publishing. “The truth about fats: the good, the bad, and the in-between.” https://www.health.harvard.edu/staying-healthy/the-truth-about-fats-bad-and-good
- Mayo Clinic. “Dietary fat: Know which to choose.” https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/fat/art-20045550
- Cleveland Clinic. “Omega-3 Fatty Acids & the Important Role They Play.” https://my.clevelandclinic.org/health/articles/17290-omega-3-fatty-acids
- Pontzer H, Yamada Y, Sagayama H, et al. “Daily Energy Expenditure Through the Human Life Course.” Science, 2021. https://pmc.ncbi.nlm.nih.gov/articles/PMC8370708/
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). “Nonalcoholic Fatty Liver Disease (NAFLD) & NASH.” https://www.niddk.nih.gov/health-information/liver-disease/nafld-nash