If you're a fan of superstar fitness trainer Jillian Michaels' tough love approach, then her 2008 "30-Day Shred" DVD does not disappoint. This classic fitness DVD offers three different workouts based around Michaels' trademark 3-2-1 interval plan, which she continues to employ in more recent workout DVDs, such as her 2012 "Ripped in 30." But as catchy and motivating as Michaels' DVD workouts can be, they still depend on the same basic exercise science behind weight-loss efforts everywhere.
You lose weight with Jillian Michaels' "30-Day Shred" DVD just as you'd do it with any other type of activity: by burning more calories than you take in, which forces your body to use stored fat for fuel.
The 30-Day Shred Explained
The 30-Day Shred DVD offers three workouts — levels 1, 2 and 3 — with the expectation that you'll start with the relatively easy level 1 and work your way through the other three levels as you feel ready. Don't let the relatively easy designation fool you.
Reviewers are quick to note that even the "beginner" level can feel brutally difficult, especially if you follow Michaels' admonitions to not exceed five-second breaks to catch your breath. No water breaks here: Michaels wants you to maximize your returns on effort by working straight through whatever level you've chosen.
Each of the workouts is based around Michaels' 3-2-1 interval plan. They follow a three-minute interval of strength training with a two-minute interval of cardiovascular exercise and a quick, one-minute interval of ab workouts.
Each workout level gives you three of those interval circuits for a total of 18 minutes of full-on exertion, sandwiched between a quick warm-up and an equally fast cool-down. All told, each level of the workout comes in at just under 30 minutes, and the only equipment you need is a yoga mat and a pair of hand weights.
Michaels' cool-down periods may seem too short for some people. If you feel like you need a little more time to cool down after your workout (or ramp up to it beforehand), don't be shy about including your own exercises before or after the DVD — or just rewind the DVD to replay the warm-up or cool-down portions until you feel ready.
Ideally, both warm-up and cool-down should last at least five to 10 minutes (although more is fine) and mimic the same movements you'll find in the full workout.
Why It Works
The weight-loss mechanism for the 30-Day Shred workout is just the same as for any other workouts: If you burn more calories than you take in in, your body is forced to burn stored fat as fuel — and so you lose weight. That said, 30-Day Shred has a few things going for it that might make it an easier way of losing weight than other DVDs or gym workouts.
- Its fast workouts are relatively easy to squeeze into a busy day.
- Michaels' instructions are easy to follow.
- For fans, her motivational style is very effective.
- The choice of three levels gives you enough variety to progress and stay entertained, but enough repetition to develop confidence.
It's hard to say exactly how many calories you'll burn with each 30-Day Shred workout because a number of factors go into determining that number, from your weight and body composition to how hard you work out. But at its heart, the Shred workout is a circuit training program, with heavy emphasis on plyometrics, or jumping exercises — an intense form of calisthenics.
With that in mind, and based on estimates from Harvard Health Publishing, a 155-pound exerciser doing 30-Day Shred workouts would burn almost 300 calories during each workout, while a 185-pound person doing the same workouts could burn roughly 350 calories.
Intense workouts like the 30-Day Shred also help create a phenomenon known as EPOC, or excess post-exercise oxygen consumption.
That's a fancy way of saying that once your metabolism revs up for that workout, it takes a while to return to a pre-exercise state. And until that happens, your body burns more calories than it normally would during rest.
Have Trouble Losing Weight?
If all goes well, you'll see quick results with an intense workout like the 30-Day Shred. But if it feels like there's a monkey wrench in your weight-loss machinery, don't panic. There are several things you can do to make that weight loss kick in.
The first is your diet. Are you eating an appropriate number of calories for your age, gender and activity level?
Next up are nutrients. Are you sticking to the key elements of a healthy eating pattern, which include eating lots of colorful fruits and vegetables plus whole grains, low-fat dairy and high-quality protein sources? You should also limit your intake of added sugar and sodium, along with unhealthy saturated and trans fats.
Last but definitely not least, are you getting enough sleep and drinking enough water? A study published in May 2019 in the journal Obesity showed that chronic sleep deprivation definitely correlates with increased body fat in children; the correlation is less clear for adults, but still worth considering.
Meanwhile, a data review published in Frontiers in Nutrition in June 2016 shows that there is a clear correlation between hydration and weight loss in rats and also in humans, although the mechanism for humans is less well understood than for rodents.
Consider Adding More Activity
The 30-Day Shred workout has one notable limitation: Because it includes a strength-training component, you should leave at least one full rest day between workouts, which means you can only do the Shred workout three or four times a week — at most.
If you're really serious about weight loss, you can supplement your 30-Day Shred workouts by adding extra activity on those "in-between" days. The more you work out, the faster the weight will come off, but make sure to focus on cardiovascular workouts so that your muscles can recover from the Shred workout's weight training.
Just a few examples of cardio in which you can engage include:
- Gym machines (treadmill, elliptical, stair climber, exercise bike)
- Biking or inline skating outside
- Walking or running outdoors
- Jumping rope
- Aerobics classes
- Dance classes or go out and dance (as long as you keep moving)
- Organized sports such as softball and soccer
- CalorieBee: "Review of Jillian Michaels' 30 Day Shred DVD (Levels 1, 2 & 3)"
- Mayo Clinic: "Aerobic Exercise: How to Warm Up and Cool Down"
- Harvard Health Publishing: "Calories Burned in 30 Minutes for People of Three Different Weights"
- University of New Mexico: "Exercise After-Burn: Research Update"
- Health.gov: "Estimated Calorie Needs per Day, by Age, Sex, and Physical Activity Level"
- Health.gov: "Key Elements of Health Eating Patterns"
- Obesity: "Sleep Duration and Adiposity in Children and Adults: Observational and Mendelian" Randomization Studies