If you’ve researched weight loss or fat loss in an attempt to achieve the body they’ve always wanted, you’ve would probably have heard about the 80/20 principle.

The widely accepted definition and use of the 80/20 rule, also known as the Pareto principle, states that, for many events, roughly 80% of the effects come from 20% of the causes.

In relation to weight loss, many in the industry use it to illustrate that 80% of your weight loss efforts should be focused on your diet, and the remaining 20% on exercise. That’s because exercise in isolation is largely inefficient at reducing weight.

An exercise in futility

A growing body of research emerging from the US and UK now shows that, in general, these studies demonstrate no or modest weight loss with exercise alone. Researchers have attributed this to a number of factors.

For instance, a University in New Jersey study published in the October 2012 edition of Obesity Review, found that “the small magnitude of weight loss observed from the majority of evaluated exercise interventions is primarily due to low doses of prescribed exercise energy expenditures compounded by a concomitant (associated) increase in caloric intake.

What this means is that most people simply don’t have enough time to exercise for the duration required to burn a significant number of calories.

For example, according to information available from the Mayo Clinic, during an hour-long exercise session – the maximum amount of time most of us have on a daily basis to train – a 73kg individual will only burn 533 calories doing high-intensity aerobics, 606 calories while jogging, 657 calories on the stepper, or 314 calories while walking.

When you consider that this is the calorie content of just one of your 4-5 small, healthy meals each day, or just two doughnuts if you indulge, you then start to realise that, from a practical perspective, exercise in isolation is not an effective way to lose weight.

Combine exercise and diet for better results

But don’t ditch the gym contract. There are benefits to a combined approach to weight loss. According to a 2011 study published in the journal Obesity that looked at the effect of diet and exercise, alone or combined, on weight and body composition.

During the year-long study on 439 overweight-to-obese postmenopausal sedentary women, researchers demonstrated that the greatest effects on weight loss and body composition were found in the combined intervention group, where 60% of participants lost 10% or more of their body weight in one year.