Exercise in Futility – Women’s Health Initiative

By Jason Fung, MD

  • Scientific studies repeatedly confirm that ‘Eat Less, Move More’ is an inefficient way to lose weight
  • Increasing exercise did not lead to more weight loss over time
  • School based interventions of ‘Eat Less, Move More’ also failed
By Jason Fung, M.D., Co-founder of The Fasting Method


The standard ‘Eat Less, Move More’ weight loss strategy was put to the test in the Women’s Health Initiative study. Simple calorie restriction – that is reducing calories without much thought about changing the foods we eat was found to be ineffective for weight loss. It also turns out that increasing exercise is also an ineffective weight loss method. There is no doubt that exercise is good for you.  But it is simply not that effective for weight loss.  As Eric Ravussin at Louisiana State University explained in Time Magazine, “In general, for weight loss, exercise is pretty useless”.

Eat Less

The Women’s Health Initiative study was a massive, expensive and ambitious National Institute for Health study published in 2006 “Low-fat dietary pattern and weight change over 7 years: the Women’s Health Initiative Dietary Modification Trial Howard BV et al. JAMA 2006; 295:39-49” Close to 50,000 women participated for an average of 7.5 years in this randomized controlled trial, the gold standard in experimental medicine.

The study diet included education sessions, group activities, interviews and personalized feedback to reduce dietary fat to 20% of daily calories, increase vegetables and fruit to 5 servings/day, and grains to 6 servings/day. The control group, by contrast, just got a copy of Dietary Guidelines for Americans.

This dietary intervention was consistent with the nutritional recommendations of the time (1993-1998), and the dietary counselling succeeded in changing behavior. Total caloric intake reduced from 1788 to 1446 calories/day – a reduction of 361.4 calories/day for over 7 years. Fat as a percentage of calories reduced from 38.8% to 29.8%. Carbohydrates increased from 44.5% to 52.7% since whole grains were encouraged.

Move More!

The second pillar of the WHI study was increased exercise. The women in the study group increased their daily physical activity from 10 METs/wk to 11.4 METs/wk. MET, which stands for ‘metabolic equivalents’ is simply a measure of physical activity. In other words, physical activity increased 14% over baseline over those 7.5 years.

The study group successfully followed a lower calorie, lower fat diet while simultaneously increasing exercise (Eat Less, Move More). Average weight at the beginning of the study was 76.8kg (169 lbs) with an average Body Mass Index of 29.1, in the Overweight (BMI 25-29.9) category but bordering on the Obese category (>30). So, what happened?


The Eat Less, Move More group starts out great with an average of more than 2kg over the first year. By the second year, the weight starts to be regained and by the end of the study, there is no significant difference between the two groups. Weight loss over 7.5 years of the Eat Less, Move More strategy was not even one single kg (2.2 lbs).

Perhaps the explanation is that women lost fat and gained muscle, so weight remained stable. This would show up as a reduced Waist-Hip Ratio (WHR), since body fat is typically carried in the waist. Unfortunately, the average waist increased from 89.0 to 90.1 cm, and the average WHR increased from 0.82 to 0.83. Not only did these women not lose weight, they were actually fatter than before.

Many people say, “I don’t understand. I eat less. I exercise more. But I can’t seem to lose any weight.” I know. I believe them. Because this advice has been proven to fail. Do caloric reduction diets work in the real world? Absolutely not.

The Effect of Exercise

The WHI study also examined in more detail that exercise portion of the study in this paper “Physical Activity and Weight Gain Prevention, Women’s Health Study”. Researchers followed 39,876 women from 1992-2004, dividing them into 3 groups representing high, medium and low levels of weekly exercise.

The group that exercised the least (<7.5 MET hours per week) did less than about 150 minutes per week.  The highest exercising group (>21 MET hours per week) did more than an hour a day. At baseline (time 0), the ones who exercised the most were the lightest, and the ones who exercised the least were the heaviest.  So far, so good. But what happened over the next 10 years? Does this advantage continue to widen with this daily exercise? You would expect that after 10 years, those who continued to exercise would continue to increase their benefits.

Surprisingly, that’s not what the research showed. Actually, there is a difference in the amount of weight lost or gained between the 3 groups.  The extra weight that you would expect to lose over any 3-year period is 0.12 kg or just over 1/4 lb. Yes, you read that correctly.  If you exercise every single day for 1 hour for 3 years, you would expect to weigh an extra 1/4 lb. less than if you did nothing at all.

Exercise is good for your health in many ways – better muscle tone, strength, bone density etc. Exercise is just not so good for weight loss. Other studies show much the same results, although the WHI study is by far the largest.


A more recent publication, the HEALTHY study, published in the prestigious New England Journal of Medicine in 2010 and entitled “A School-Based Intervention for Diabetes Risk Reduction“. 42 schools and 4603 students in grade 6-8 took part over 3 years, with half getting the multicomponent intervention encouraging students to:

  • Lower average fat content of food
  • Serve at least 2 servings of fruit and vegetables per student
  • At least 2 servings of grain-based food and/ or legumes
  • Increase time spent doing moderate to vigorous physical activity

In other words – our old dingleberry friend – Eat Less, Move More. Not too bright, but as familiar as an old blanket. Did students lose more weight using this approach? Did it work? Not even a little bit. By the end of three years, both groups had reduced that percentage to about 45%.  In other words – there was no measurable benefit to this diet and exercise group compared to doing nothing special. It’s virtually useless for weight loss.

For more, see The Obesity Code.

Learn more about Pique Fasting Tea.

For fasting education, support and community, go to The Fasting Method.

Jason Fung, MD

By Jason Fung, MD

Jason Fung, M.D., is a Toronto-based nephrologist (kidney specialist) and a world leading expert in intermittent fasting and low-carb diets.

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