I've been exploring some critical questions … whose answers aren't always clear.

How much exercise – and what kinds – really help enhance our health, and in what ways?

And while these are all wonderful reasons to work out, many of us need to exercise simply to get back to a healthy weight. 

Having tried a variety of approaches to getting (and staying!) fit, I wondered, what kind of exercise is best if we want to lose weight?

A look at BMI
There are a number of ways to determine your "ideal” weight range.

The National Institutes of Health recommends assessing your weight by looking at two factors: Body Mass Index (BMI) and waist circumference.

A larger waist measurement indicates that you're carrying the majority of your "extra” weight around your middle (rather than at your hips), meaning you may be at higher risk of heart disease and type-2 diabetes.

Your risk goes up when your waist is larger than 35 inches for women or 40 inches for men.

To get an accurate measurement, take a deep breath, exhale, and then measure around your middle just above your hip bones.

The second factor, Body Mass Index (BMI), is a calculation based on your height and weight, and is a relatively accurate measure of your risk for heart disease and other diseases related to your levels of body fat.

There are of course limitations to BMI – it's a less accurate measure of total body fat for people with muscular builds and for older people who may have lost significant muscle mass.

You can use an online calculator to determine your BMI. Once you have that, here's a guide to what your results mean:
  • Underweight = <18.5
  • Normal weight = 18.5-24.9
  • Overweight = 25-29.99
  • Obese = 30+
Calorie control vs. exercise
If your BMI falls in the 25-plus range, you may need to lose weight to protect your long-term health.

I definitely fall into this category and am constantly striving to figure out the right balance of diet and exercise to lose weight.

What I've learned is that without regular workouts, it almost doesn't matter much I watch my caloric intake – for me, I have to work out to shed pounds.

Studies confirm this finding as well – while you have to cut calories to lose weight, exercise is essential to helping you keep the pounds off. In fact, calorie-cutting without exercise often leads to regaining of weight lost.

Dieting versus dieting plus exercise
You can absolutely lose weight without exercise … many people do.

But studies show that calorie-cutting plus increased activity delivers the best results.

A year-long study published in 2012 looked at the effects of three approaches in 439 overweight, post-menopausal women (Foster-Schubert KE et al. 2012):
  • Calorie-reduced diet
  • Aerobic exercise
  • Combination of calorie cutting plus aerobic exercise
  • No changes (control group).
The diet group, exercise group and combo groups all showed significant weight loss over the course of 12 months (the control group showed few changes).

But the greatest change was seen in the group that combined diet plus exercise, with 10.8% of body weight lost, compared to 8.5% in the diet-only group and just 2.4% in the exercise-only group.

Which kinds of exercise are best for weight control?   
Scientists have struggled with the answer to this key question.

Which type of exercise – aerobic (cardio), strength, or strength plus aerobic – makes the biggest difference to body weight and body composition?

Aerobic exercises are things like running, swimming, and cycling, while the most common strength exercises involve weight lifting or resistance-exercise machines.

Oddly, relatively few studies have sought to discover which kind of exercise is best for weight loss, and instead focused on changes in body composition (the proportions of fat versus muscle).

Duke University studies suggest an answer
Twenty years ago, researchers at Duke University Medical Center conducted a clinical trial designed to test the effects of aerobic exercise and resistance training on body weight (Willis LH et al. 1985).

Their eight-month study involved 119 middle-aged, sedentary, overweight/obese volunteers who were randomly assigned to one of three exercise regimens:
  • Aerobic exercise
  • Strength training
  • Combined aerobic and strength exercise
The results showed that aerobic exercise resulted in the greatest loss of body fat and body weight alike.

Unsurprisingly, the regimens that included strength exercise built more muscle … and studies suggest that over time, developing greater proportions of muscle versus body fat helps prevent weight gain.

In 2012, another team from Duke University Medical Center published the results of a similar eight-month trial involving 117 previously sedentary people.

As in the previous Duke study, the participants were assigned to perform aerobic exercise, strength exercise, or a combination of the two types.

After eight months, all of the volunteers lost weight and reduced their total calorie intakes (Bales CW et al. 2012). Those results undermine the idea that exercise tends to boost calorie intake … though that may be the case over the short term.

New Spanish diet+exercise study supports all forms of exercise
A recently published clinical trial from Spain seems to support the findings from the Duke studies.

However, it differed in that although the participants exercise, they also radically reduced calorie intake.

The Spanish research team recruited 96 overweight adults (half men, half women) for a 22-week trial, in which all the participants followed a calorie-reduced diet (30% fewer calories than they burned a day).

Each participant was assigned to one of four groups:
  • Aerobic (running, cycling or elliptical)
  • Strength training (a variety of upper and lower body exercises)
  • Combination of aerobic and strength training
  • Participant choice (200-300 minutes of activity per week; activity, intensity and duration of their choosing)
The participants in the first three groups exercised at the same intensity three times per week, working up from 51 minutes to 60 minutes over the course of the 22-week study.

All of the participants enjoyed significant weight loss, lower BMI (Body Mass Index), smaller waist measurements, lower overall body fat, and a boost in lean muscle mass at the end of the 22-week study.

The type of workout didn't matter at all ... any kind of weekly activity, plus calorie reduction, resulted in big improvements.

That result that echoes the outcome of the 2012 Duke study, but differs from those of the 1985 Duke study, which found that aerobic exercise produced more weight loss. 

The radical calorie-cutting required of the participants in the Spanish study means that its results aren't quite as "clean" as either of the two Duke exercise studies, which did not involve simultaneous calorie-cutting.

Judging by the results of the studies from Duke and Spain, we should do the type of exercise we like best, and ideally combine it with calorie control.

Current exercise guidelines
Setting weight loss aside, how much exercise do we need to stay healthy? 

The Office of Disease Prevention and Health Promotion takes a science-based approach to developing weekly fitness guidelines.

The current guidelines, established in 2008, recommend 150 to 300 minutes of moderate-intensity activity (such as a brisk walk) or 75 to 150 minutes of vigorous-intensity aerobic activity (running, biking, jogging,or swimming at a reasonably intense level).

Ideally, these minutes are spread out over most of the days of the week.

So, for example, the upper levels of their recommendations would mean a 60-minute walk or a 30-minute run five days a week.

They also recommend muscle-strengthening exercises of a moderate to intense level, using most of the major muscle groups, two or more days a week.

Have you found that a certain type of activity has best helped you lose weight? What are your weight loss secrets?

I'd love to hear from you – please email me and let me know!

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