In the ever-evolving landscape of weight loss strategies, calorie cycling has emerged as a flexible and potentially effective approach for those seeking to shed pounds and improve overall health. Unlike traditional calorie restriction diets that often leave individuals feeling deprived and prone to rebound weight gain, calorie cycling offers a more dynamic method of managing energy intake. Calorie cycling, also known as calorie shifting or an intermittent energy restriction diet, is an eating pattern in which you cycle your calorie intake from day to day or week to week. This approach aims to outsmart the body's natural tendency to adapt to prolonged calorie restriction, potentially leading to more sustainable weight loss results.
Understanding Calorie Cycling
The Basics of Calorie Balance
Calorie balance is fundamental to weight management. It's the relationship between the energy consumed through food and drink and the energy expended through daily activities and bodily functions. To lose weight, you must create a calorie deficit by consuming fewer calories than your body burns. The NHS recommends that most adults should reduce their daily calorie intake by 600 calories to lose weight at a safe and sustainable rate of 0.5kg to 1kg (1lb to 2lb) per week. For most women, this means sticking to a calorie limit of no more than 1,400kcal a day.
What is Calorie Cycling?
Calorie cycling takes the principle of calorie balance and adds a dynamic element. Instead of maintaining a constant calorie deficit, this approach involves alternating between higher and lower calorie days. The core idea is to prevent the metabolic slowdown often associated with prolonged calorie restriction while still achieving an overall calorie deficit over time. There are no food restrictions or strict guidelines, just the number of calories you can eat on certain days or weeks. For this reason, it’s not a “diet” in the conventional sense, but rather a way of structuring your weekly or monthly food intake.
A basic example of a calorie cycling plan might look like this:
- Monday (High-calorie day): 2,200 calories (workout day)
- Tuesday (Low-calorie day): 1,600 calories
- Wednesday (Medium-calorie day): 1,900 calories
- Thursday (High-calorie day): 2,200 calories (workout day)
- Friday (Low-calorie day): 1,600 calories
- Saturday (Medium-calorie day): 1,900 calories
- Sunday (Low-calorie day): 1,600 calories
This pattern allows for higher calorie intake on days with more intense physical activity, potentially supporting better workout performance and recovery.
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Potential Benefits of Calorie Cycling
Research suggests the benefits of calorie cycling include greater weight loss, improved ability to stick to a diet, less hunger, and a reduction in the negative hormonal and metabolic adaptations of a normal weight loss diet.
Increased Metabolism
One of the primary theories behind calorie cycling is its potential to prevent the metabolic slowdown often associated with traditional dieting. When we consistently eat fewer calories, our bodies may adapt by reducing energy expenditure - a survival mechanism that can hinder weight loss efforts. By alternating between higher and lower calorie days, calorie cycling aims to keep the metabolism guessing, potentially preventing this adaptive response. A study published in the International Journal of Obesity found that participants following a calorie cycling approach experienced less of a decrease in resting metabolic rate compared to those on a continuous low-calorie diet.
Improved Appetite Control
For many women, managing hunger and cravings is one of the most challenging aspects of weight loss. Calorie cycling may offer some advantages in this area by helping to regulate hunger hormones and blood sugar levels. On higher calorie days, the increased food intake can help satisfy cravings and provide a psychological break from feeling restricted. This may lead to better adherence to the overall plan. Additionally, the variation in calorie intake may help regulate hormones like leptin and ghrelin, which play crucial roles in appetite control. By incorporating a mix of complex carbohydrates, lean proteins, and healthy fats across both high and low-calorie days, calorie cycling can support stable blood sugar levels.
Muscle Preservation
Maintaining muscle mass is crucial for long-term weight management and overall health, especially for women as they age. Traditional low-calorie diets can sometimes lead to muscle loss alongside fat loss, which can negatively impact metabolism and body composition. Calorie cycling, particularly when combined with resistance training, may help preserve muscle mass during weight loss. The higher calorie days provide additional energy and nutrients to support muscle repair and growth, especially when timed around workouts. A research study found that participants following a calorie cycling approach while engaging in resistance training maintained more lean body mass compared to those on a continuous low-calorie diet.
Implementing Calorie Cycling
Determining Your Calorie Needs
Before embarking on a calorie cycling plan, it's crucial to determine your baseline calorie needs. This involves calculating your Total Daily Energy Expenditure (TDEE), which takes into account factors such as age, height, weight, activity level, and goals. While online calculators can provide a rough estimate, consulting with a registered dietitian or healthcare professional can offer a more accurate and personalised assessment. The NHS provides general guidelines for calorie intake, but these should be adjusted based on individual factors and weight loss goals.
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Creating a Calorie Cycling Plan
Once you've determined your baseline calorie needs, you can create a personalised calorie cycling plan. Here's a step-by-step guide:
- Determine your weekly calorie deficit goal (e.g., 3,500 calories for 0.5 kg of weight loss per week).
- Decide on the number of high, medium, and low-calorie days based on your schedule and preferences.
- Allocate calories across the week, ensuring an overall deficit while allowing for higher intake on more active days.
Tips for Success
To successfully implement calorie cycling, consider the following tips:
- Plan meals in advance, especially for low-calorie days.
- Focus on nutrient-dense whole foods across all calorie levels.
- Use a food diary or app to track calorie intake accurately.
- Stay hydrated, aiming for at least 6-8 glasses of water daily.
- Incorporate regular physical activity, including both cardio and strength training.
- Practise mindful eating, paying attention to hunger and fullness cues.
- Be patient and consistent - sustainable weight loss takes time.
Combine Calorie Cycling with Exercise
Since exercise plays an important role in health and weight loss, it makes sense to tailor your calories to your activity level. The varying demands of exercise can drastically change your calorie needs on any given day. Therefore, it makes sense to schedule your longest and most intense exercise sessions on high calorie days. On the other hand, save the lighter exercise sessions or rest days for your low calorie days. Over time, this can allow you to lose fat but still maximize performance when it’s most important. Base your high calorie days and refeeds around intense training blocks or sessions, and tailor your low calorie periods around training that’s less intense or less of a priority.
Important Considerations
Not a Magic Bullet
Calorie cycling offers potential benefits, but it's crucial to understand that it's not a miraculous solution for weight loss. While this approach can be an effective tool for some individuals, it must be integrated with a balanced, nutritious diet and regular physical activity to achieve long-term success. Developing healthy lifestyle habits remains essential and cannot be replaced by any single dietary strategy. Experts in nutrition and dietetics emphasise that sustainable weight management requires a comprehensive approach that goes beyond simply manipulating calorie intake.
Not for Everyone
Calorie cycling may not be suitable for everyone. Individuals with a history of eating disorders, pregnant or breastfeeding women, and those with certain medical conditions should avoid this approach. Additionally, some people may find the constant calorie tracking too stressful or time-consuming. The NHS provides comprehensive advice on healthy eating and weight management, which may be more appropriate for those who prefer a simpler approach.
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Research on Calorie Cycling
Some studies have found sharp declines in the number of calories people burn per day when cutting calories. In one 2014 study, participants spent 11 days on a low calorie diet followed by 3 days of eating more calories (termed a “refeed”). Four weeks after treatment, some significant weight loss and fat loss had started, and both continued up to a 1-month follow-up. In other cases, studies have looked at longer 3- to 4-week diets with 1-week refeeds. As shown in the graph below, a 2001 study found almost a 250-calorie reduction in calories burned at rest after 8 weeks on a weight loss diet. Another study found that a 3-week low calorie diet decreased metabolism by more than 100 calories. However, when participants switched to a higher-calorie diet in the fourth week, their metabolism increased to above starting levels. A 7-week study of resistance-trained participants found that during an energy-restricted diet, a consecutive 2-day carbohydrate refeed more effectively prevented the loss of fat-free body mass than continuous energy restriction. Those participants’ resting metabolic rates were also slightly better maintained. A review found that intermittent energy restriction diets had more effect on weight loss than continuous energy restriction diets, but the researchers noted that longer trials are necessary to confirm this. However, other research has found little difference between the benefits of intermittent and continuous energy restriction diets. Research reviews in 2021 and 2018 concluded that the two types of diet have similar effects on weight loss. Overall, according to the National Institute on Aging, more research is needed to fully understand the long-term health benefits of calorie cycling. Research suggests that an intermittent energy restriction diet with periodic high calorie days may increase your metabolism and hormone levels more successfully than a continuous energy diet, but further studies are needed.
Calorie Restriction and Metabolic Adaptation
Calorie restriction (CR) is the most potent, non-pharmacological intervention to support metabolic health. The effects of calorie restriction exceed weight loss. Consistent throughout many studies, calorie restriction induces a reduction in energy expenditure that is larger than the loss of metabolic mass, i.e. fat-free mass and fat mass, can explain. From a physiological standpoint this likely relates to the composition of body weight loss, reductions in insulin secretion, thyroid and leptin concentrations, and increased mitochondrial energy efficiency. Behavioral factors including physical activity and eating behaviors likely also play a role, specifically to prevent weight regain. Assessing the effects of CR on energy metabolism requires distinction between individual components of total daily EE. Total daily EE is partitioned into the energy expended at rest (resting EE), in response to meals (diet-induced thermogenesis), and to support physical activity (activity-related EE). Resting EE is measured by indirect calorimetry either with a bedside ventilated hood system, or in a whole-room metabolic chamber (Lam and Ravussin, 2016). Diet-induced thermogenesis can be measured with the same methodologies performed before and after consumption of a meal, yet is routinely assumed to equate to 10% of total daily EE (Tataranni et al., 1995). Activity-related EE then is calculated as the difference between total daily EE and resting EE plus diet-induced thermogenesis. A decline in EE which is beyond what would be expected relative to the changes body mass (or composition) is termed metabolic adaptation. Metabolic adaptation was the primary outcome of the CALERIE studies and was investigated after 3 and 6 months of 25% prescribed CR in CALERIE Phase 1, and after 12 and 24 months in CALERIE Phase 2. As hypothesized, after 6-24 months of CR, metabolic adaptation was observed during sleep (Heilbronn et al., 2006; Redman et al., 2018), at rest (Martin et al., 2007; Ravussin et al., 2015), over 24 h in the confined environment of the room calorimeter (Heilbronn et al., 2006; Redman et al., 2018), and over 14-days in free-living conditions (Ravussin et al., 2015; Redman et al., 2009; Redman et al., 2018). The metabolic adaptation observed during sleep, which is arguably the most reproducible measure of metabolic rate, was 8% at 3 months, 7% at 6 months, 6% at 12 months, and 5% at 24 months. In contrast the metabolic adaptation in free-living conditions was almost double at each time point across the 24-month period (13% at 3 months, 7% at 6 months, 8% at 12 months and 9% at 24 months, respectively). The larger metabolic adaptation in free-living conditions suggests that the culprit of such adaptations is not only changes in metabolic processes but also compensations in behaviors likely occurring in an effort to conserve energy. Importantly, body weight loss occurred only during the first 6-12 months, after which time it was maintained. This implies that metabolic adaptation is not exclusive to periods of chronic energy deficiency, but that it persists in energy balance. The cause of metabolic adaptation appears to be specific to calorie restriction because studies that demonstrated exercise-induced weight loss did not observe metabolic adaptation (Hopkins et al., 2014; Jennings et al., 2009; Karstoft et al., 2017; Lee et al., 2009; Mourier et al., 1997).
Conclusion
Calorie cycling offers a flexible and potentially effective approach to weight loss and wellness for British women. By strategically varying calorie intake, this method aims to overcome some of the challenges associated with traditional dieting, such as metabolic slowdown and muscle loss. However, it's crucial to remember that sustainable weight loss and improved health come from developing long-term healthy habits. Calorie cycling should be viewed as a tool within a broader approach that includes balanced nutrition, regular physical activity, and overall lifestyle improvements. Before starting any new diet or exercise regimen, always consult with a healthcare professional or registered dietitian to ensure it's appropriate for your individual needs and health status. With the right approach and support, calorie cycling could be a valuable strategy in your journey towards better health and wellness.