Does high-intensity interval training live up to the hype?

When it comes to exercise, people usually subscribe to the notion that “more is better.” Many health organizations recommend at least two hours of moderate exercise a week, claiming that ramping up to five hours or more confers even more health benefits.

What if the key to getting the most out of exercise wasn’t the amount, but the intensity? What if you could get as many (if not more) benefits from as little as a couple minutes of exercise a week as opposed to several hours?

It may sound like I’m a television fitness guru that’s trying to sell you a series of DVDs, but I’m not. What I’m talking about is high-intensity interval training or HIIT. The time commitment is low and the benefits are real.

The time commitment is low and the benefits are real for high-intensity interval training (HIIT) Click To Tweet

How do HIIT and traditional exercise differ?

Exercises such as jogging, walking or cycling are usually given shorthand names like steady-state cardio or aerobic exercise. Their key features are that the intensity is low to moderate and the time commitment is usually 30 minutes or more a session.

In contrast, HIIT is characterized by extremely short periods of all-out intensity (such as sprinting) followed by timed rest periods. Watch this clip from an episode of BBC’s Horizons series. It shows how short, but intense HIIT can be:

 

Why you may want to cut back on long-term steady-state cardio

Doing things like going for a short, daily walk or participating in a yoga class is great for your health. Research reviews continually show that regular physical activity is helpful in managing and preventing chronic diseases like diabetes and high blood pressure.

However, when people commit large portions of time to steady-state cardio activities (think Iron Man participants and endurance athletes), the health benefits start to taper off and negatives can be the unfortunate result.

While lots of cardio may seem healthy, consistently overdoing it may result in negative health effects Click To Tweet

Studies from the Mayo Clinic, Journal of Applied Physiology, Medicine and Science in Sports and Exercise and the European Heart Journal have found endurance athletes show abnormal thickening of heart valves, a potential sign of heart failure.

That same population has been found to have highly-elevated levels of cortisol (a stress-response hormone), increased C-reactive protein (a sign of inflammation) and exhibit symptoms like immune system deficits, sleep difficulties and mood disturbances.

What are the benefits of HIIT?

Whereas too much long-term steady-state cardio can have negative effects on an individual’s heart, low volumes of HIIT (around three sessions a week) can improve heart artery stiffness and cardiovascular functions.

Studies have shown HIIT to have many other benefits such as:

How do you perform a HIIT session?

Some online guides complicate HIIT, calling for things like mixing free weights with bodyweight squats. An effective HIIT session really can be as simple as the video clip above from BBC Horizons.

If you’re just starting and/or want to keep things simple, stick with one form of cardio, such as sprinting or cycling on a stationary bike. Then follow a template such as this up to three times a week:

How to perform a HIIT session

Test your knowledge of superfoods

While exercise and lifestyle factors are important to overall health, so is diet, and that’s why it’s important to make your food choices count.

Superfoods are foods that are nutrient dense, meaning they pack many healthy benefits into every bite. Want to test your superfood knowledge? Take the quiz below.

Every Monday, we showcase a new superfood on Facebook, Google+, Twitter and Instagram

[playbuzz-game game=”http://www.playbuzz.com/houstonmethodist10/how-much-do-you-know-about-superfoods”] 

The meal frequency myth

“Eating five to six mini meals a day … keeps your metabolism humming 24/7,” proclaims a Redbook article. “Have a small meal or snack every 3 to 4 hours keeps your metabolism cranking,” notes a WebMD slideshow

You’ve probably heard similar statements—all based on the assumption that food grazing increases your basal metabolic rate (BMR) or the number of calories used in a day, leading to more fat loss.

Is there any truth to this? Are six meals a day better than three? And what about fasting? Does skipping meals negatively impact your health?

Deconstructing the metabolic fire analogy

Advocates of increased meal frequency usually compare BMR to a fire. If you think of a fire, the fuel is wood and when wood is thrown on an existing fire, more fire is produced, throwing off heat.

If you apply this analogy to people, the wood is calories from food and the reaction that produces heat is the thermic effect of food (TEF), which is the amount of energy your body has to expend to process food for storage and use.

Take a look at the chart below the bulleted list. It compares TEF for three people who eat the same amount of calories and macronutrients (fats, carbohydrates and protein):

  • One eats six meals a day (breakfast, a mid-morning snack, lunch, an afternoon snack, dinner and an evening snack)
  • One eats the traditional three meals a day (breakfast, lunch and dinner)
  • One eats only two meals a day (breakfast and dinner)
Screenshot_061
This chart compares the thermic effect of food (TEF) during a day for three people who eat the same amount of calories and macronutrients, but eat in different patterns.

While the TEF spike duration and frequency is different, the total amount of TEF for all three individuals is identical. This means the amount of calories used in a day is the same, regardless of meal frequency.

The amount of calories used in a day is the same, regardless of meal frequency Click To Tweet

Research confirms this: Studies in both 1997 and 2010 noted as long the total amount of food eaten is the same, you can gorge or nibble—neither approach promotes more or less weight loss than the other.

Returning to the fire analogy, eating less but more frequently is like continually throwing kindling on the fire all day long whereas eating more in a sitting (but less frequently) is like throwing a big log on the fire.

What about fasting?

Many are fearful to skip meals because they hear that fasting lowers your BMR, putting your body into starvation mode.

This is oversimplified and inaccurate. It may be true that fasting decreases your BMR, but with one big caveat: It takes over three days of fasting to accomplish this.

In fact, researchers have found that short-term fasting actually increases the amount of calories you burn while at rest and doesn’t affect cognitive performance, activity, sleep or mood.

Could fewer meals be better for you?

A lot of recent research has come out in favor of eating less frequently. For example, a 2014 study found that frequent snacking might stress the liver, leading to a greater risk of fatty liver disease.  

Fasting for short periods of time has been found to have the following health benefits:

Numerous studies have shown that short-term fasting has health benefits and fewer meals may be better for you Click To Tweet

And lowers the risk of:

Eat the way that works for you

There’s no reason to stress out about meal frequency. If you find it easier to make healthy food choices by eating a couple of meals a day and a snack or two, then stick to that. If you like to spend more of the day fasting so you can enjoy larger meals and because it suits your schedule, then stay with that approach.

When it comes to weight loss, overall calories matter more than meal frequency, so always keep an eye on your portions. If you have issues with blood sugar control, work with your doctor to figure out a meal schedule that works for you. 

Reviewed by Kristen Kizer, R.D.

Is high fructose corn syrup worse than sugar?

Not a week goes by in the media without stories about potential health problems associated with high fructose corn syrup (HFCS). From brands like Yoplait to Heinz and Hunt’s, consumers are asking for the removal of the ingredient from products and companies are responding.

However, what do you really know about HFCS? Is it the main culprit when it comes to weight gain and metabolic problems or is there more to the story? In order to tackle this subject, let’s first look at HFCS and sugar at the molecular level.

Up close and personal: HFCS and sugar

Time for a little biochemistry: The kind of HFCS used in packaged foods and soda goes by the names HFCS 55 and HFCS 42. In the 55 variant, 55% of molecules are fructose and 42% are glucose. For HFCS 42, the breakdown is 42% fructose and 53% glucose. Both fructose and glucose are basic, simple forms of carbohydrates.

At the molecular level, high fructose corn syrup and sugar are nearly identical Click To Tweet

Why did I provide that molecular breakdown? Sucrose or sugar often replaces HFCS when brands swap ingredients and guess what? It has a 1:1 ratio of glucose to fructose, meaning that 50% of the molecules are fructose and 50% are glucose. At the molecular level, HFCS and sugar are nearly identical.

sucrose
This image shows the molecular layout of sucrose or sugar. 50% of it is fructose and 50% is glucose, making it a near mirror molecular image of high fructose corn syrup.

Research roundup: HFCS vs. sugar

Given that HFCS and sugar have a very similar glucose-to-fructose ratio, what does the nutritional literature have to say about the health effects of HFCS?

According to a 2008 study, “Sucrose and HFCS do not have substantially different short-term endocrine/metabolic effects.” Even when looking at other critical factors like appetite- and fat-related hormones, no difference has been found between sugar and HFCS.

A 2012 study that put subjects on a reduced-calorie diet noted that both the HFCS and sugar group lost similar amounts of weight and body fat, leading researchers to conclude the type of sugar in the diet was of no significance.

All these results are similar to a 2007 critical review in Food Science and Nutrition, which summed up its research saying, “The currently available evidence is insufficient to implicate HFCS per se as a causal factor in the overweight and obesity problem in the United States.”

The real nutritional culprit: excess carbohydrates

It may seem like I’m letting HFCS and sugar off the hook, but I’m not. What’s important to realize is that they’re both carbohydrates and because of their connection to “sweetness,” they shift the conversation away from something people need to be more aware of when it comes to their diet: too many carbohydrates elevates blood sugar.

Note how sugar consumption ramped up  in the early '70s. While sweetener choice has changed with time, one aspect has remained constant: Americans are eating more simple carbohydrates.
Note how sugar consumption ramped up in the early ’70s. While sweetener choice has changed with time, one aspect has remained constant: Americans are eating more simple carbohydrates. Image source: Austin G. Davis-Richardson (Wikipedia)

A diet composed of too many insulin-spiking carbohydrates has been implicated in the following health problems:

Too many insulin-spiking carbohydrates may lead to heart disease, diabetes and macular degeneration Click To Tweet

Making healthier choices

Elimination of foods containing HFCS is a great start to revamping one’s diet as HFCS is typically found in processed foods that contain artificial ingredients, little nutrient density, low fiber counts and hydrogenated vegetable oils.

But don’t be misled: eating the same amount of a food that uses sugar or a similar sweetener in the place of HFCS won’t lead to significant improvements in your health.

Instead, shop the perimeter of the grocery store, stocking up on fibrous fruits and vegetables like berries, avocados and broccoli, and protein sources like wild-caught salmon and grass-fed beef. It’s all about increasing the nutrient density of your food choices and being a more aware consumer.

Reviewed by Kristen Kizer, R.D.

3 science-backed ways to improve your sleep

You toss and turn and can’t get to sleep. The next morning, instead of being alert and ready to take on the day, you find yourself dragging—dependent on coffee for a morning boost. For many, something as integral to our nature as sleep seems elusive.

Night Owl Surfing the Net
Are you a night owl? If you are, your body may produce less melatonin, a hormone tied to sleep and wake cycles that’s also a potent antioxidant.

From weight gain to increased cardiovascular risk to even accelerated aging, poor sleep quality can be disastrous to your health.

Improving your sleep can boost your immune system, increase athletic performance and improve your memory.

Here are three ways to improve your sleep and make sure you get a good night’s rest.

Minimize your exposure to blue light after sunset

The pineal gland in your brain produces the hormone melatonin. In turn, melatonin helps regulate sleep and wake cycles, causing drowsiness at appropriate times.

Not only does melatonin help sync sleep patterns, it functions as a potent antioxidant that is as effective as vitamin E and has been found to significantly reduce cellular stress and damage. The best part? It’s naturally produced by your body.

Melatonin helps regulate sleep, but is disrupted by artificial light from devices like tablets and smartphones Click To Tweet

For melatonin to be produced, you must be exposed to natural patterns of light, meaning lots of bright light during the day and minimal blue light at night. To maximize melatonin production, consider following these tips:

  • Wear amber-tinted, blue-blocking sunglasses after sunset if you’re exposed to electronic screens or bright lights
  • Studies in 2009 and 2011 found that wearing these kinds of glasses help combat disruptions in melatonin
  • If you have a sleep disorder or do shift work, replace house lights you use in the evening with amber light bulbs
  • Install blue-blocking software like Twilightf.lux or Redshift  on your computer, tablet and/or smartphone
  • Make your bedroom as dark as possible by covering windows with heavy drapes
  • Turn electronic devices that emit light off or away from your bed

Eliminate late-night meals and snacking

Don’t raid the fridge after dark or eat dinner too late. A 2011 study found that eating late in the evening extended the time it took individuals to get to sleep and reduced overall sleep quality.

Research shows that eating too late at night disrupts melatonin production, as well as raising levels of the stress hormone cortisol, which is naturally supposed to be high in the morning, not evening.

Research shows that eating late at night extends the time it takes to get to sleep and reduces sleep quality Click To Tweet

So, what seems to be the sweet spot for meal timing at night? Research leans toward keeping your evening meal about four hours away from bedtime.

Don’t drink alcohol near bedtime

While many like a nightcap, it’s not the best idea as far as sleep goes.

A small amount of alcohol (such as a glass of wine) may make it easier to fall asleep, but any amount of alcohol disrupts the second half of your sleep cycle, which is important for concentration, motor skills and memory.

While alcohol may seem to help you fall asleep, it results in a less restorative sleep cycle Click To Tweet

Ladies take special note: You metabolize alcohol differently than men, absorbing 30% more in your bloodstream. This means alcohol disrupts sleep more in women than in men.

Interested in learning more about sleep? Follow our Sweet Dreams board on Pinterest.

Follow Houston Methodist’s board Sweet Dreams on Pinterest.

Reviewed by Aparajitha K. Verma, M.D.