Fitness expert Denise Austin swears by the 80/20 rule after trying diet fads for 4 decades

• Fitness expert Denise Austin said after trying many diets, she always went back to the 80/20 rule.
• That means eating healthy 80% of the time, with plenty of protein and veggies.
• The other 20% can be treats you enjoy, which can help you stick to your diet long term.

Denise Austin has tried everything. From the low-fat craze of the '90s to vegan and vegetarian diets to low-carb Atkins and its resurgence as the keto diet, the home-fitness pioneer has spent her whole career seeking out the best advice on healthy eating.

After 40 years in the health industry, she always comes back to the same diet rule - eat healthy, nutrient-dense food about 80% of the time, and save the other 20% for foods that you enjoy, regardless of nutritional value.

This is sometimes known as the 80/20 rule, and it's a strategy for healthy eating you can stick to for years, and even decades, Austin, who recently launched Fit Over 50 magazine, told Insider in an interview.

"I love food and believe in enjoying yourself," she said. "I've learned so much more about how to eat well for healthy aging, and it's about feeling good too."

Include plenty of protein and veggies in your diet, along with a daily treat

Austin, who has a line of protein snacks called Ever Better, said she tried to balance healthy sources of carbs, fat, and protein for most of her diet.

Getting enough protein can help you feel more satisfied after eating and energized throughout the day. Austin also recommends prioritizing fruits and vegetables for their vitamins and micronutrients, which are important for a healthy digestive system.

The other 20% of Austin's calories are for fun foods, whether it's dessert after dinner or a margarita at the end of the day. About one treat per day, such as a doughnut or serving of ice cream, is a good frame of reference.

Try new things, but don't be afraid to ditch things that don't work for you

Austin said that she loved to learn about fitness and nutrition trends and the evidence behind them.

"I've tried everything because this is my livelihood and what I love, so I really want to know what works," she said.

During her forays into other diets, she's incorporated benefits from multiple trends. For instance, she didn't stick to a high-fat, low-carb keto diet, but she said trying it made her more mindful of sticking to healthy sources of carbohydrates, such as fruits and veggies, instead of refined grains.

Similarly, dabbling in the paleo diet highlighted the importance of whole, unprocessed foods, she said.

"I've always been a true believer in balance. I like a little of everything," she said.

Keeping a balanced and flexible diet can help you stay consistent with your nutrition long term, experts say.

For example, if you're trying to eat healthier for summer, it's best to find a diet you enjoy enough to stick to afterward, which means avoiding too much restriction.

"If you think cutting carbs is the most effective, but it makes you die inside, don't do it," Georgie Fear, a registered dietitian, previously told Insider.