For those of you who have attempted to lose weight at some point in your life, you’ll be aware of how much of a long old slog dieting can be.
Not only can a sustained period of dieting pull on energy reserves and make even the simplest of tasks feel significantly more gargantuan, it can be a mental push too.
Long term weight loss success is of great interest to personal trainers and weight loss clients simply because it is so hard to achieve. As you’ve probably read before, the majority of people who diet end up putting even more weight back on. I’d estimate that a couple of the reasons for this include restricting certain foods (and therefore increasing the want for them twofold), and dieting for too long.
One possible solution to this problem is the diet break – a period of time, generally 1 to 2 weeks, where you eat at maintenance calories (enough to sustain your current body weight).
The idea is that you diet for a couple of weeks, dropping weight on a calorie intake that would ensure a certain percentage of weight loss each week, and then maintain your body weight with a slightly higher calorie intake for a couple of weeks. Benefits could include the psychological relief, a decrease in the hunger hormone ghrelin that rises in the presence of a caloric deficit, and an increase in the satiety hormone leptin that decreases in the presence of a caloric deficit. You’d then be in a prime position to reignite the dieting process.
Without looking at the research, I see benefits to this method with someone who has already been dieting continuously for a long time. However, generally when people embark on a mission to lose weight they want continuity and momentum to ensure they see as much weight come off as quickly as possible. I’d be extremely reluctant to introduce a diet break two weeks into a weight loss plan when my client is in a groove and feels motivated.
Now, turning to two research studies that have been conducted on diet breaks, it’s clear to see that my hypothesis is largely correct.
Byrne et al, 2017 – The MATADOR study
Fifty-one men with obesity were randomised to 16 weeks of either: (1) continuous, or (2) intermittent energy restriction completed as 8 x 2 week blocks of energy restriction alternating with 7 x 2 week blocks of energy balance (30 weeks total). Essentially, the second group dieting for 2 weeks and then maintained body weight for 2 weeks.
Participants in the second group lost more weight overall and maintained an average loss of 8kg more than the continuous diet group 6 months after the diet.
Findings from the study suggest that the utilisation of diet breaks could be an effective long-term strategy for sustainable weight loss and deactivating obesity rebound. However, 30 weeks is a long time and it is possible that while participants were instructed to eat at a caloric intake that would ensure weight maintenance every 2 weeks, they may have continued to drop weight during this period.
Peos, Helms, Krieger et al, 2021 – Continuous vs Intermittent Dieting for Fat Loss
A a very similar study published just this year, renowned fitness researchers Jackson Peos, Eric Helms, James Krieger and colleagues looked at 61 adults with an average body fat percentage of 25%. Generally, you’d describe a person with at 25% body fat to be slightly overweight, but certainly not obese.
Participants were randomised to 12 continuous weeks of moderate energy restriction or 4 x 3 weeks of moderate energy restriction interspersed with 3 x 1 weeks of energy balance (15 weeks in total). Both groups performed strength training throughout.
Diet breaks did not result in lower fat mass, body weight or greater fat free mass despite performing three more weeks of strength training compared to the continuous diet group.
There were no differences between groups for leptin, testosterone, insulin like growth, free T3 thyroid or active ghrelin. Similarly, no significant differences were noted between groups for sleep quality, irritability, muscle dysmorphia, control over eating, over mood, eating disorder behaviours or behavioural consequences of hunger.
Diet breaks did however result in lower levels of hunger and desire to eat with greater food satisfaction.
Conclusions
- For those with more weight to lose (i.e. obese individuals), diet breaks may be an effective intermittent strategy to help with long-term weight loss
- A period of continuous dieting is probably necessary before resorting to diet breaks
- Diet breaks may help individuals break through weight loss plateaus
- A 12-week transformation probably doesn’t need to include a diet break
- A maintenance period following a period of dieting probably isn’t necessary
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