We’ve all heard that a safe rate of weight loss is between 1-2 lbs (or 0.5 to 1 kg) per week. Yet the reality is that few people are content with losing only 4 lbs per month and are likely to engage in more extreme diet control strategies in an attempt to expedite the rate of weight loss. Could there a downside to losing weight quickly? Is rapid weight loss more likely to be regained compared to weight that is lost more gradually? In today’s post, we’re taking a closer look at the science behind this weight loss recommendation.
You Can’t Control Your Weight
Before we delve deeper, I want to take a few minutes to discuss this sentiment. Because when I say you can’t control your weight, what I mean is that we are not in control of the number on the scale; the only things we can control are our health habits (check out this blog[SM1] to read more about health habits). Above all, if you burn more calories than you consume, you will lose weight. But, since our bodies are designed for survival – and weight loss is seen as a threat to our survival – your body will do everything it can to stop the weight loss and restore homeostasis. This isn’t to say that weight loss is impossible and there is no point in trying. Rather, it means tying success to a specific weight loss goal can be both fruitless and emotionally draining.
Slow and Steady vs. Rapid Results
The widespread recommendation for
slow and steady weight loss seems to be based more on clinical opinion than
scientific study, as few research articles have been carried out to investigate
the impact of rapid vs. gradual weight loss on long-term weight status.
One randomized controlled trial
(1) found that participants regained similar amounts of weight over a 3-year
period (approximately 70% of lost weight) regardless if the weight was lost gradually
(> 12.5% weight loss achieved over 9 months) or rapidly (>
12.5% weight loss achieved over 3 months). Similarly, a more recent study
(2) found that despite comparable rates of weight loss, a 12-week low calorie
diet (1250 calories per day) compared to a 5 week very low-calorie diet (500
calories per day) resulted in nearly identical rates of weight regain during
the 9 month-follow-up period (58.6% and 54.7%, respectively).
Based on these results, it seems
that the rate of weight loss has little to do with our ability to keep weight
off since weight regain was an inevitable outcome for most. So perhaps the
discussion needs to shift from a focus on weight loss and how quickly we can
reach our goal weight to how we will maintain any weight we do lose.
Permanent weight loss requires permanent behaviour change. And if you need to grit your teeth and white-knuckle your way through these behaviour changes, it’s unlikely that you will be able to maintain them for long. As cliché and redundant as it sounds, long-term weight loss requires a change in lifestyle that is enjoyable or, at the very least, tolerable. So, before committing yourself to a grueling exercise program or swearing off all carbohydrates, take a moment to consider if these behaviour changes can be lifelong. If the answer is no (as I suspect it is), then look for a way to modify the behaviour so it is both enjoyable and sustainable. And keep in mind that all of the research to date suggests that the best diet is the one that you follow for the rest of your life.
Purcell K, Sumithran P, Prendergast LA, Bouniu
CJ, Delbridge E, Proietto The effect of rate of weight loss on long-term
weightmanagement: a randomised controlled trial. Lancet Diabetes Endocrinol.
Vink RG, Roumans NJ, Arkenbosch LA, Mariman EC,
van Baak MA. The effect of rate of weight loss on long-term weight regain in
adults with overweight and obesity. Obesity (Silver Spring). 2016
Feb;24(2):321-7. doi: 10.1002/oby.21346.