A nutritionist swears by the 'triple 30' rule to eat enough protein and fiber for gut health and longevity

Forget proteinmaxxing — a simple three-part rule can help you hit your goals without overdoing it, says a top nutritionist in the UK.

Dominique Ludwig has been helping people eat healthfully for three decades. She said most diet trends offer contradictory advice, wasting your valuable time, money, and energy.

"In a world where nutrition is very confusing, it can actually be really simple," she told Business Insider.

Ludwig's new book, "No Nonsense Nutrition," offers a road map for healthy eating principles that work for both her and her clients.

One of her favorite tips is the "triple 30" rule: eating 30 grams of protein at each meal, 30 grams of fiber each day, and at least 30 different plants in your diet each week.

Ludwig said that within four weeks of following the triple 30 rule, her clients can cut back on processed foods without feeling deprived or relying on complex or strict eating plans.

As a result, they often have reduced cravings and "food noise," better digestion, lower inflammation (which may translate to fewer aches and pains), better mood, and more energy.

"Sometimes you don't need to jump down every rabbit hole. If you just start with the foundation, you suddenly see that food actually can be one of the most transformational things we can do to our health," Ludwig said.

Eat protein at every meal

You're probably already getting enough protein, Ludwig said, but timing it correctly can help you feel full throughout the day.

"It stabilizes your blood sugars. It keeps you feeling fuller for longer," she said. "Having your protein in the morning is really important because if you get breakfast right, it sets the bar for the rest of the day."

She recommends aiming for around 30 grams of protein at each meal through sources like Greek yogurt, fish, chicken, or legumes.

That's about 90 grams of protein per day, although you may need more if you're larger or highly active. Research suggests that adults benefit from around 1.5 grams of protein per kilogram of body weight (or 0.7 grams per pound) daily.

Getting the right amount of protein is also important for a long, healthy life, and we generally need more as we get older to prevent age-related loss of muscle tissue and promote a healthy metabolism.

"Proteins are not only for our muscles, but they're also for repair, they support our immune system, and our neurotransmitters. They're really important," Ludwig said.

Aim for 30 grams of fiber a day

While protein gets all the attention, Ludwig said fiber is an underrated nutrient that supports gut health, weight loss, and more.

"We're living in this massive fiber gap at the moment," she said. "It's the missing link."

Getting enough fiber helps slow digestion, which can promote steadier blood sugar and energy levels, helping you feel more satisfied after meals.

"Protein and fiber are like this dynamic duo; together they're bulky, and that means they switch on all these satiety mechanisms," Ludwig said.

She recommends 30 grams a day, slightly more than typical dietary advice, based on research from the American Gut Project, a study of more than 15,000 people led by the University of California San Diego, that analyzed health and eating habits.

High-fiber diets — rich in foods like beans, nuts, and whole grains — are also linked to a lower risk of chronic illnesses like heart disease and colorectal cancer, making fiber a key nutrient for longevity, too.

Include a variety of plants in your diet

The final 30 in Ludwig's formula refers to including 30 different types of plants in your diet each week, to provide a wide range of nutrients for gut health.

Your digestive system hosts colonies of beneficial bacteria, your microbiome, which play a key role in health, from your mood to your energy levels.

Ludwig compared the microbiome to a zoo: just as giraffes prefer different foods from lions, each type of gut microbe thrives on different micronutrients found in different plants.

Loading up on 30 plants a week is easier than you might think: every little bit counts, from the herbs and spices in your pantry to your morning coffee or tea.

And, she said, don't forget to treat yourself: fresh fruits, popcorn, and dark chocolate all help support a healthier gut in the long term.