It wasn't too long ago that Americans would buy just about any food product labeled "low fat" in their quest to lose weight. But a funny thing happened during the low-fat craze -- we got fatter.

The reasons for why we got fatter can be debated (I think widespread overeating of highly processed low-fat foods that substituted simple carbohydrates for fats played a role), but suffice it to say we were all operating under some false assumptions. Perhaps the biggest one was that all fats are bad, which is absolutely not true. Many fats are good for you and should have a regular place in our meals.

Good fats typically come from oils in fish, nuts and plants. Many of them contain high amounts omega-3 fatty acids, which research indicates can help you live longer and simply feel better. Below are some fatty foods that are much healthier than a lot of low-fat products.

Fish Research has shown fish oil may be able to help you live longer, reduce the risk of heart attack and dementia, lower blood pressure and improve eye health. Keep in mind that cold-water fish are the healthiest to eat. These include salmon, sardines, mackerel, halibut and, to some extent, tuna. One serving of fish a week is enough to get the requisite health benefits. One caution about fish: Don't fry it. When you do, its oil turns unhealthy -- kind of a dietary Jekyll and Hyde.

Nuts: The unsaturated fats in many nuts are believed to improve heart health and even reduce bad cholesterol. Nuts that are good for you include walnuts, almonds, pecans and pistachios. Eat them raw if possible because roasted nuts often have been prepared in a way that eliminates their nutrients. Consume nuts in moderation since they are high in fat and calories.

Olive Oil: I love olive oil. It's my go-to oil for cooking and it's what I use on salads. You might have recently read about the key role olive oil plays in the so-called Mediterranean diet, which researchers suggest reduces the risk of heart disease and stroke. Be careful not to overheat olive oil when using it as a cooking oil to, say, sauté vegetables. If it begins smoking then it's too hot and goes from being good for you to being unhealthy.

Avocados: Avocados are full of protein and nutrients. They also have fairly high amount of fat, which is why people avoided eating them during the low-fat craze. But avocados have healthy fat, including omega-3s.

I don't want readers to think it's good to eat all kinds of fat now. Trans-fats and, to a lesser degree, saturated fats are indeed bad for you and increase your risk of heart disease. So it's important to be able to discern good fats from bad ones. A simple rule of thumb is that healthy fats are usually liquid at room temperature; unhealthy fats (including most animal fat) are solid at room temperature. And just remember: not all fats are bad for you and not all foods labeled low-fat are good for you.

Tzvieli is a family physician at Contra Costa Regional Medical Center & Health Centers. Send questions to series coordinator Dr. David Pepper at theairdoctor@gmail.com.

For more health information, go to www.cchealth.org.