💥 Choose a PN program for FREE—when you join the PN Nutrition Certification for $59/month


💥 Choose a PN program for FREE—when you join the PN Nutrition Certification for $59


Become a Certified Nutrition Coach

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  • Make a great living helping people transform their health
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Meet the Experts

Helen Kollias



Helen Kollias, PhD, is PN’s science advisor and coauthor of Precision Nutrition’s Level 1 Certification textbook, The Essentials of Nutrition and Coaching. An exercise physiologist, Dr. Kollias earned her doctorate in Molecular Biology from York University in Toronto, specializing in the area of muscle development and regeneration. She has a master’s degree in Exercise Physiology and Biochemistry from the University of Waterloo, and has taught exercise physiology, molecular biology, and biochemistry at the university and college level.

Before joining Precision Nutrition, Dr. Kollias held research positions at some of the most prestigious institutions in the world, including Johns Hopkins and Toronto’s Hospital for Sick Children. She has been published in 10 scientific journals in exercise physiology and molecular biology.

Facebook: HelenKolliasPhD
Twitter: @hdkollias

Articles by Helen Kollias, PhD

Menopausal woman sleeping

Menopause and sleep: The struggle is real (and, by the way, so are these solutions)

Sleep disruptions are caused by many different factors, not just hormones.

Man sitting on a running track, looking down, holding a bottle.

What are BCAAs—and are they worth it?

Here’s the truth, according to science.

Chart showing the relationship between blood glucose levels and time. Minutes is on the x-axis; blood glucose (mg/dl) on the y-axis.

Carbs, insulin, and weight loss: What REALLY matters for getting the results you want

Some experts believe carbs and insulin cause weight gain. But, they say, if you eat a low-carb diet, you’ll keep insulin levels low—and lose weight fast. Learn the truth… and find out what matters most for losing fat.

Athletic man and woman sitting drinking protein shakes

‘How much protein should I eat?’ Choose the right amount for
fat loss, muscle, and health.

Will too much protein damage my kidneys? Cause cancer? Reduce my lifespan? At Precision Nutrition we're always getting questions (from fitness pros and clients) about the risks of a high-protein diet. In this article we'll set the record straight and share why protein isn’t the villain it’s made out to be.

Case study:
The Biggest Loser

"Will decades of dieting mean a broken metabolism?" It's a common anxiety. Case in point: The Biggest Loser, whose contestants are famous for dramatic weight loss — and for the devastating regain that sometimes follows. In this article, we break down a study examining exactly what happened to their metabolisms — and what this means for everyone else who wants to lose weight and keep it off.

The surprising problem with calorie counting. [Infographic]

Think meticulous calorie counting means knowing exactly how much breakfast you’re burning during exercise? Unfortunately, it’s more complicated than that. Here, 4 reasons why daily activity tracking and exercise counts can be problematic.

The surprising problem with calorie counting. [Infographic]

Most people who count calories for weight loss or weight management assume it’s an exact science. It’s not. Here we outline 5 reasons calorie counting (i.e. logging your food to calculate intake) is fundamentally flawed.

Are GMOs bad for your health?

GMOs are such a hot topic nowadays. With so many people debating the pros and cons, it’s hard to know what to think. So let’s answer the question: Are GMOs bad for you health? And then let’s look at a few other important questions.

Headshots of women surrounding text.

Does intermittent fasting work for women?

Intermittent fasting works for some women, while others have problems. Read the latest research on intermittent fasting for women to see if it's right for you.

Fish oil and omega-3 fats: How to be safer with your supplements

Fish oil and omega-3 fats:

Everyone knows that fish oil is awesome. It’s full of omega-3 fatty acids, which do so many fantastic things in the body. Indeed, for the last few years almost every health expert has recommended a varied intake of omega-3 fats as well as fish oil supplementation. However, lately, fish oil has come under fire. Some claim that fish oil could be hurting instead of helping us. That we’re consuming too much. That we’re in danger. In today’s article, we’ll review the latest research paper that’s confused and bewildered many people. And we’ll help you make sense of the controversy.

Carbohydrate tolerance: Is your ability to eat carbs determined by your genes?

Carbohydrate tolerance:

Ever wonder why some people can eat bushels of bananas without gaining a pound, but you seem to gain weight by just looking at a potato? Maybe it’s your genes. But just because you’re “carb intolerant” doesn’t mean you’re doomed. These simple guidelines can help.

Cardio vs. weights:

Contrary to recent headlines, aerobic exercise alone is not a recipe for faster fat loss. Instead, a combination of resistance training and aerobics will lead to the most impressive, and longest lasting improvements in body composition.

Weight loss & hunger hormones:

Short-term very-low-calorie dieting disrupts powerful hormones that control appetite, hunger, and satiety for up to a year after a strict diet. Crash diet now, feel hungry later... even several months later. Only long-term, slow and careful dedication to building new healthy habits works for permanent fat loss.

Research Review:

Whey protein digests quickly while casein digests slowly. In this experiment, researchers tried to determine whether fast digestion or slow digestion is better for protein synthesis and muscle building. The conclusion? Fast digestion is best for boosting muscle protein synthesis.

Research Review:

A program of regular weight training decreased blood pressure in middle aged hypertensive men. Consider exercise before you rush to medicate yourself.

Research Review:

When is a calorie not a calorie? When it's from whole versus processed food. Digesting foods costs energy. We expend more energy (calories) digesting whole foods than processed foods. Thus, if you want to lose fat, choose whole foods as often as possible.

Leptin, ghrelin, and weight loss.

Leptin and ghrelin are hormones with important roles in regulating appetite and hunger. And both hormones and their signals can get messed up with obesity.

Research Review:

Is it true that "too much" protein will harm your kidneys? We put this theory to the test with a group at high risk for kidney disease.

Research Review: 2 years of low-carb – what happens?

Which diet -- low-fat or low carb -- is best for long-term weight loss and general heart health?

Research Review: How do omega-3 fatty acids work?

Helen Kollias justifies her incessant omega-3 pushing, arguing that omega-3s are like a giant roadblock... for inflammation.

Research Review:

Drinking two cups of water before a meal will keep you hydrated, fuller, and may even boost your metabolism for an hour. And all you need to do is turn on your tap. Talk about convenience.

Research Review: Anabolic hormone release = more muscle?

You may have heard the old-timers at your gym say, "If you want big arms, squat." They mean that the hormonal release generated by large exercises improves overall muscle gain results. But is that true?

Research Review: Thick or thin? Which bar is best?

When AC/DC sang, "We've got the biggest bars of them all!" (what? those aren't the right lyrics?) were they referring to the improved grip strength and muscular activation from thick barbell training? This week's study finds out!

Research Review: Big squat, fast sprint?

As Will Ferrell opined in Talladega Nights, "I wanna go fast!" Don't we all? Is a big squat the secret to a fast sprint?