Fat Burning Workouts for Women: The Dirty Little
Want to know the dirty little secret about fat burning workouts for women? Almost any workout can be a fat loss workout so long as it helps you expend more more calories than you’re taking in overall. Of course, there are some workouts that better lend themselves to fat burning more than others.
For example, you may be familiar with the “fat burning zone.” According to Dr. Sue Kleiner, RD, in her article, “The 3 Biggest Fat Burning Myths For Active Women,” the “fat-burning zone” is “also known as submaximal exercise, or training at 45 to 65% of your VO2max. This moderate exercise intensity depends on a mix of about 55% fat to 45% carbs for fuel, and requires a moderate amount of total calories per minute of exercise.
On the other hand, high-intensity exercise, 70% and higher of your VO2max, requires at least 72% of the total calories burned to come from carbohydrates, meaning less than 28% of the calories burned come from fat, and the higher the intensity, the more your body depends on carbohydrates, rather than fat, for fuel.”
That said, it is theorized that high-intensity exercise can lead to an elevated post-exercise metabolic rate, also know as excess post-exercise oxygen consumption (EPOC), or ‘after-burn.’ Dr. Sue explains, “That after-burn can last for 24-36 hours and is typically fueled mostly by fat, whereas with moderate-intensity cardio, there isn’t much of a post-exercise increase in your metabolic rate. There’s no ‘after-burn’ of calories.”
While there is no argument that EPOC can exist, the conditions required to make it come about seem to be very specific and difficult to achieve. Findings suggest that subjects need to be in energy balance (i.e. not dieting) and work at much harder efforts than are safe or even possible for most exercisers1. Even these conditions result in mixed research findings, such as found in a comprehensive review article of the effects of various intensities of training on 24-hour fat oxidation in subjects not dieting2.
The main criticism of HIIT lies in advertising it as a fat loss miracle, and suggesting people stop wasting their time with moderate intensity cardio.
Most programs advertise that you can do HIIT for a much smaller period of time, usually less than 20 minutes, rather than that typically 30-45 minutes of moderate intensity cardio. If you work intensely or moderately for the same amount of time, you will of course burn more calories working intensely. However, this isn’t how HIIT is advertised, and performing high intensity exercise for a prolonged period of time may be impossible, or potentially risky for most people. This leaves people doing a 15-20 minute circuit and wondering why their fat loss isn’t going as planned.
Several critiques have been written illustrating the negligible impact HIIT will have on overall fat loss, considering the large calorie deficit that is needed to lose even 1 lb of fat. Moreover this review and many others have proven that without energy restriction, exercise of any type or intensity makes a negligible dent in weight without very large volumes of exercise, which are unrealistic for most people.
A recent study at Duke University compared three 8-month exercise protocols to induce fat loss: aerobic exercise, resistance training of the same duration, and a combination of two (resulting in twice the total exercise time). The guidelines were based on the current ACSM recommendations for health and fitness. Every group was instructed to keep their diet consistent.
Every group lost some fat mass, but the resistance only lost the least, while the combined program, unsurprisingly lost the most. However, this was only 2.5kg (roughly 5 lbs) of fat on average over 8 months in overweight individuals. Most people trying to lose body fat would be pretty disappointed with only a 5 lb loss over 8 months. A recent meta-analysis confirmed these findings when comparing programs that are diet-only, physical activity only or a combined program, showing that diet only is superior in the short term, but combined programs are most effective for long-term fat loss or maintenance of fat loss.
Bottom line? Exercise of any type should be viewed as an enhancement, rather than a means, to fat loss. Nutrition is critical when fat loss is your goal.
When choosing what type of exercise to engage in, keep in mind you will be more likely to stick to a program for fat loss that you enjoy, that works for your schedule, and doesn’t increase your risk for injury or aggravate any existing conditions.
Finally, despite not being as effective at fat loss as nutritional adjustments, cardiovascular activity of any intensity has numerous benefits beyond fat-burning, including:
- improved recovery
- improved sleep quality
- increased ability to deal with stress
- increased work capacity that allows you to train more intensely for longer periods with less fatigue
All of those benefits create conditions that more effectively support your fat loss efforts.