Introduction
Dieting for weight and fat loss is an endeavour most of us have attempted at some point in our lives, whether wanting to lose weight to improve our health markers or reducing body fat to improve performance outcomes, the motivation to do so is often varied, as too are the results. In a meta-analysis of 29 long-term weight loss studies, more than half of the lost weight was regained within two years, and by five years more than 80% of lost weight was regained. It is unsurprising then, that individuals repeatedly try and fail in their weight loss attempts, resulting in the belief that weight loss is but a futile endeavour.
Before we dive into the concept of diet breaks and how they can be effectively implemented for long-term fat loss, it is important to understand the basic mechanisms that drive weight and fat loss. The laws of thermodynamics in relation to weight management state that calories in versus calories out govern the degree to which one will lose weight. Simply put, if you consume less calories than you expend, you will experience a net loss in bodyweight. Sounds so simple right? Then why is it so many people fail to maintain weight loss? The reality is that long-term weight loss is complex due to interactions between our biology, behaviour, and the obesogenic environment. Highly processed, hyper palatable, calorie dense foods are everywhere, whilst the environment will now live in (particularly in western society) has become more sedentary as people’s general activity levels are on the decline. These changes in food and physical activity create the perfect storm of increased intake and decreased expenditure, resulting in weight gain over time.
So what is the solution?
Firstly you must ask yourself the question, ‘why do I want to lose weight and/or body fat?’ An individual that is obese who wants to lose weight in order to improve their general health markers is very different to an athlete who wants to lose weight to improve performance or make weight for competition. Regardless of your goals, the challenge is to engage in a diet that you enjoy and that you can adhere to. There are no end of diets to try; Keto, high carb, low carb, high fat, low fat, flexible dieting, if it fits your macros, the list goes on! We know that adherence is fundamental to the long-term success of a weight loss programme. Therefore, if you can plan and structure your dietary approach in such a way that it isn’t too restrictive and ridged the literature would suggest you would have an increased chance of long-term success. Interestingly, studies that implemented a concept called ‘diet breaks’, found that not only did individuals achieve their weight and fat loss goals to the same degree as individuals on a continuous diet of calorie restriction, but more importantly, they were more likely to maintain their fat loss goals long-term compared to individuals utilising a continuous dieting approach. So let’s take a closer look at diet breaks, the pros and cons and how you can implement these concepts into your own diet plans.
Diet breaks; what are they and are they effective?
Diet breaks can be definite as a deliberately scheduled break from a diet, whereby calories are increased to an estimated ‘maintenance’ dose for a set period of time. There are a number of variations within this dietary approach, which we will touch on later, as this will be important to understand when you are putting together your own nutritional plans.
The original diet break study by Wing and Jeffrey (2003) assigned participants into three groups (control, long break and short break) and each of the groups underwent a weight loss programme, consisting of an energy restricted diet, as well as a progressive exercise programme. Nutrition and exercise were logged and daily weigh-ins were recorded. After 20 weeks, the study found that all three groups lost a similar amount of weight, despite the diet break groups essentially having periods where they were ‘off’ the diet. During these ‘off’ periods it is important to acknowledge that daily caloric intake was not prescribed or closely monitored, which could have potentially lead to overfeeding as a compensatory mechanism, subsequently inhibiting the weight loss progress.
A more recent study by Byrne et al., (2017) went a stage further when implementing a diet break strategy. In their study, calorie intake was much more tightly controlled and meals were provided to the participants both during periods of energy restriction (33% energy deficit), as well as during the diet break, whereby daily calorie intake was matched for energy maintenance. This allowed for total calories to be accurately calculated and tracked throughout the total duration of the study. Interestingly, the results of the study found that the group that intermittently used diet breaks lost 50% more body fat and weight than the group that maintained a constant dieting approach. Furthermore, losses in lean muscle mass were similar between groups and the diet break group also experienced a 50% less reduction in resting energy expenditure (REE). All this would appear to indicate a significant benefit of utilising diet breaks for weight and fat loss, and more importantly weight loss maintenance.
Mechanisms
Some of the proposed physiological mechanisms of implementing diet breaks surround the body being more resistant to metabolic adaptation. Metabolic adaption or adaptive thermogenesis, as it is otherwise known, can be characterised as a series of adaptive responses the body undergoes due to prolonged periods of calorie restriction. A summary of these adaptions are as follows:
- BMR (basil metabolic rate) will decrease because a person weighs less
- TEF (thermic effect of food) decreases because a person is eating less
- NEAT (none exercise activity thermogenesis) typically decreases as a person eats less food so that the body can conserve energy
- EAT (exercise activity thermogenesis) decreases as fewer calories are burned because a person weighs less
- Hunger hormone ghrelin increases and satiety hormone leptin decreases
The up-regulation of REE as seen in the Byrne study following the implementation of diet breaks would appear to be a useful tool in negating some of the challenging side effects of metabolic adaptation. Another important consideration is the psychological benefits of intermittent periods of calorie restriction. Anecdotally, I have found the clients and athletes I have coached have a much easier time adhering to periods of energy restriction if broken down into blocks. They tend find it much easier to stay motivated and be disciplined for a few weeks, knowing that they will have a 1-2 week period of maintenance calories where they can increase their consumption of foods, before returning back to a period of energy restriction. In my experience I have found that this also tends to lead to a reduced likelihood of clients engaging in over-compensatory eating behaviours post diet, therefore minimising the probability of weight rebound. This too was shown to be true in the Byrne study as they concluded a greater overall weight loss, weight loss maintenance, reduced incidence of overeating both during and post diet, when diet breaks were periodically introduced.
Summary and practical applications
- Whether you are a member of the general population wanting to lose weight to improve your overall health or an athlete wanting to reduce body fat to enhance performance or lose weight for competition, the evidence base would support the implantation of diet breaks as an effective tool to aid these weight management goals, both acutely and longitudinally over time.
- Despite their effectiveness, a weight and fat loss approach utilising diet breaks are time sensitive, and as such, appropriate timescales need to be implemented for athletes or individuals needing to make weight and/or body compositional targets for competition. Strength athletes in particular may benefit from alternative approaches to weight loss for competition, therefore diet breaks may be more conducive to physique athletes and recreational trainers.
- The enhanced weight and fat loss effect that diet breaks facilitate, would appear to have both a physiological (mitigating adaptive thermogenesis) and psychological (better buy-in and adherence) component.
- Until a dose-response for diet breaks is found, it is important to encourage experimentation with the structure of a periodised diet. Any of the following plans below could be implemented successfully as part of a fat loss strategy:
| Weeks at calorie deficit | Weeks at maintenance calories | |
| Plan 1 | 4-8 | 1-2 |
| Plan 2 | 3-4 | 1-2 |
| Plan 3 | 2-3 | 1-2 |
- Final considerations should be made with regards to exercise. The study by Wing and Jeffrey (2003) implemented resistance exercise alongside their dietary intervention. It could be hypothesised that an appropriate resistance training protocol undertaken alongside one of the plans above in table 1 would alleviate any potential losses of lean mass as well as reduce the impact of metabolic adaptation. Periods at calorie maintenance could also be effectively implemented to allow increases in training intensities and volumes during a periodised training cycle and thus may serve to further enhance results via improved mindset and adherence of the individual undertaking such interventions.
Conclusion
If you are an individual who has lost weight or body fat in the past but struggled to maintain those losses over time, frustratingly rebounding back and forth again and again, then implementing diet breaks periodically may provide a solution to long-term sustainable weight and fat loss. Just remember to make sure you are clear on exactly why it is you are dieting, the impact it may have on your training and don’t forget to set a realistic time frame to achieve your goals.
References:
Byrne, N.M., et al., Intermittent energy restriction improves weight loss efficiency in obese men:the MATADOR study. Int J Obes (Lond), 2017.
Wing, R.R. and R.W. Jeffery, Prescribed “breaks” as a means to disrupt weight control efforts.Obesity Research, 2003. 11(2): p. 287-291.