Summer is here, and many of us eagerly anticipate basking in the sun, lounging by the pool, and feeling confident in our favourite swimwear. If you're looking to shed a few kilos before the swimsuit test or "la prova costume" as we say in Italy, you're not alone! This post provides an overview of modified alternate-day fasting (MADF) as an alternative weight loss approach to conventional low-calorie dieting. It also discusses the effectiveness and safety of MADF based on the latest scientific research, and offers some practical tips to ensure your summer slimdown journey is a success. Let's plunge right in!

AI-generated image of a woman diving into a lake.

What is MADF?

MADF is a type of intermittent energy restriction that involves alternating between "diet days" of very-low-caloric intake (500 calories or 600 calories if exercising) and "feast days" of unrestricted eating. (1) For instance, you might have fasting days on Monday, Wednesday, Friday, and Sunday, and feasting days on Tuesday, Thursday, and Saturday, and then switch the pattern the following week. On fasting days, you can consume your food all at once or as small meals throughout the day, (2) and they can be high or low in fat as long as they are within the calorie limit. (3) Additionally, you can have no-calorie drinks like water (still or sparkling), black coffee, unsweetened tea, and sugar-free gum on fasting days.

Is MADF Effective for Weight Loss?

Multiple systematic reviews and meta-analyses in adults have demonstrated that MADF can be an effective weight loss strategy if you are overweight or obese. (1, 4, 5, 6) Participants typically achieved a moderate reduction in body weight, ranging from 3kg to 9kg, along with reductions in fat mass, ranging from 2kg to 6kg, over a period of 3 to 12 weeks. Notably, when MADF was combined with endurance exercise, individuals experienced even greater weight loss, almost doubling the amount. (7) While the research on MADF's long-term effects is limited, other trials on intermittent energy restriction have suggested the possibility of weight loss plateaus at around the six-month mark. (4, 8) In such cases, making adjustments to macronutrient ratios, fasting duration, incorporating exercise, or even taking temporary breaks from MADF could help overcome these plateaus.

MADF's effectiveness in promoting weight loss can be attributed to a combination of synergistic mechanisms. Firstly, it creates a negative energy balance by generating a weekly calorie deficit (as long as one avoids overeating on feast days), which in turn stimulates the breakdown of stored fat, particularly the harmful visceral fat around the belly area. (9) Additionally, MADF preserves muscle and lean tissue, thus supporting a healthy basal metabolic rate and favourable body composition. (1, 5, 7, 10) This preservation ensures that the majority of weight loss primarily comes from fat, although it's worth noting that lean individuals may experience more loss of lean tissue. (11) Furthermore, MADF enhances metabolic flexibility, enabling the body to efficiently switch between different fuel sources like fat and glucose. (12) This improved flexibility optimises the utilisation of stored fat for energy while fasting, thereby aiding weight loss and promoting overall metabolic function. Finally, MADF may activate Sirtuin1 (SIRT1), a protein that contributes to fat metabolism and glucose regulation, further enhancing fat burning and metabolic processes. (13)

Is MADF Easy to Follow?

Dietary adherence is a key factor in achieving successful weight loss. (14) In fact, some argue that adherence is even more important than the diet itself. (15) MADF stands out by offering simplicity and flexibility, making it an attractive option for those who struggle with continuous calorie counting and restriction.

Simple. With just two types of days - fasting days and unrestricted days - MADF is easy to understand and follow. On fasting days, you consume 500 calories (or 600 calories with exercise), while unrestricted days allow for ad libitum eating.
Flexible. During fasting days, you have the freedom to choose your preferred foods within the calorie limit. This flexibility enhances satiety and overall satisfaction, reducing the likelihood of overeating. (3, 16)
No chronic deprivation. While it is encouraged to maintain healthy eating practices, (3, 17) MADF allows you to indulge in any foods you desire on feast days, avoiding feelings of chronic deprivation and making the diet more sustainable in the long term. (7, 18)

Is MADF Safe and Who Should Avoid it?

MADF is generally considered a safe approach, although some individuals may experience side effects during the initial weeks, such as headaches, fatigue, light-headedness, irritability, constipation, and hunger. (18, 19) These symptoms are typically mild and tend to diminish as the body adapts to the new eating pattern. Staying well-hydrated and ensuring adequate electrolyte intake can help alleviate these effects. However, there are certain populations for whom MADF is not recommended. Infants and children, as well as individuals who require regular food intake (e.g., type I diabetics, the elderly, pregnant or lactating women) should avoid MADF. Additionally, those with a current or history of eating disorders (e.g., anorexia), individuals taking certain medications (e.g., weight loss, lipid or glucose-lowering drugs), and those who are underweight should also not engage in MADF. (19)

Who should avoid MADF:
• Infants and children
• Type I diabetics
• The elderly
• Women that are pregnant, trying to conceive, or lactating
• Individuals taking medication for weight loss, lipid control, or glucose management
• Individuals with a current or past history of eating disorders
• Individuals who are underweight

Moreover, certain populations have been excluded from most research studies on MADF and should exercise caution, including individuals with liver, respiratory, renal, gastrointestinal, or cardiovascular disease, individuals with type II diabetes, cancer, epilepsy, or clinical depression, those with conditions that may be worsened by fasting (e.g., Gilbert Syndrome or thyroid disease), (20) and individuals with a history of bariatric surgery. (2, 7, 10, 21) In all these cases, it is essential to consult with a healthcare professional before attempting MADF.

Summary

In summary, based on current evidence, MADF appears to be a safe and effective approach for weight loss and management in the short to medium-term, particularly for healthy adults with excess weight. However, more research is needed to fully understand its long-term effects and safety for the general population, including older individuals and those with specific health conditions. To conclude this post, here are a few practical tips for implementing MADF successfully:

Plan ahead. Prepare your meals in advance for fasting days, or at least mentally plan what you'll eat to resist temptations.
Prioritise protein and fibre on fasting days. Including protein-rich foods helps reduce hunger and maintain muscle mass, (3) while fibre adds satiety without adding excessive calories.
Salt your food. Fasting, along with factors like exercise, low-carbohydrate diets, or warm climates, can deplete electrolytes. Liberally salt your food to help maintain proper electrolyte balance.
Join a support group. Connecting with individuals on a similar journey can provide valuable moral support and motivation. Consider joining the "Alternate Day Fasting (ADF)" group on Facebook, which boasts a large community of over 25,000 members.

If you want to explore MADF further, I recommend checking out the following books: "The Every-Other-Day Diet" by Varady and Gottlieb, and "The Alternate-Day Diet" by Johnson & Laub.

✨ Happy MADFasting!