In Part 1, we explored how our energy balance system regulates energy intake and expenditure and our genes’ role in determining our individual body weight.
We then reviewed changes in the energy balance system when using food restriction alone to lose and then maintain weight loss.
Most importantly, I explained the need to approach weight loss and weight loss maintenance as distinct phases for long-term success.
Here, I’ll review the best strategy for the weight loss and weight-loss maintenance phases and outline the characteristics of people who have been successful at weight- loss maintenance.
There’s some debate as to the best weight loss strategy. Should it be food restriction alone? Exercise alone? Or a combination of both?
Let’s see where the evidence stands on this.
Food restriction without exercise can lead to weight loss, and exercise without food restriction can, too. However, when using food restriction alone, there’s a loss of muscle mass in conjunction with fat mass (1). Even though the number on the scale may be going down, it’s at the expense of the more metabolically active fat-free mass (2,3). And when using exercise alone, significant amounts are necessary (4), which is often challenging to sustain.
What about combining food restriction and exercise? Studies show that combining the two can increase weight loss compared to either strategy alone (5). However, they differ in how much weight participants lost (6,7).
Regardless of the amount of weight lost, there are substantial health benefits when combining them.
Exercise can result in body composition changes (without significantly altering the number on the scale) – notably, “preferential loss of body fat and maintenance of fat-free mass” (8). With food restriction, these changes can lower blood pressure, and improve cardiac function, blood sugar control, mood, and sleep quality, to name a few (9,10).
Ultimately, while food restriction alone or exercise alone can lead to weight loss, the best strategy is to combine them. Doing so improves health and prepares you for the weight loss maintenance phase.
Note: There’s no need to go on a specific diet (i.e., low-carbohydrate, low-fat, Mediterranean, etc.). Weight loss studies looking at different macronutrient compositions show little difference in weight loss (11–13).
A common approach to weight loss maintenance is trying to achieve energy balance (at the new lower weight) through food restriction alone. This strategy seldom works because it’s challenging “to eat less for the rest of your life” (14).
That’s why, even though increasing physical activity isn’t necessary for weight loss – but highly recommended for overall health – it’s a critical factor in keeping the weight off (15,16).
As you lose weight, resting energy expenditure (a.k.a. your metabolism) decreases because it takes less energy to fuel a smaller body (3). As such, to stay at your new lower weight, energy intake must permanently be lower than before weight loss.
Since food restriction is hard to maintain indefinitely, physical activity allows energy intake to increase (while maintaining weight loss) by acting as a buffer against a decrease in metabolism (17). Otherwise, increasing energy intake without simultaneously increasing physical activity will lead to weight regain.
Who succeeds in maintaining weight loss?
Much of the data on weight-loss maintenance success comes from long-term observational studies of the National Weight Control Registry (NWCR), which has over 10,000 members.
Within the registry, successful long-term weight loss maintenance refers to “intentionally losing at least 10% of initial body weight and keeping it off for at least 1 year” (18). With this level of success, even if there is some weight regain, there are still health benefits to maintaining this degree of weight loss (19).
Here are the common strategies used by NWCR members (20):
- High levels of physical activity
- Diet low in calories and fat
- Eat breakfast regularly
- Self-monitor weight regularly
- Maintain consistent eating patterns (throughout the week)
Also, there are certain factors associated with weight regain (20):
- Disinhibited eating (periodic loss of control of eating)
- Significant decreases in physical activity
- Increase in percent of calories from fat
- Decrease in dietary restraint
While it’s good to know the strategies used by NWCR members, how can we translate this into something tangible – where do we start?
Follow me to Part 3 to find out.