Study: How our fasting box can support men who want to have children
Insights from a recent study on the Fasting Mimicking Diet
A new study in which we participated at Salufast (published in Frontiers in Nutrition, 2025 ) shows that repeated short-term fasting based on the fasting mimicry diet (FMD) may potentially benefit men with impaired sperm quality. This is accompanied not only by physiological but also psychological effects: The authors primarily discuss the feasibility and acceptability of FMD, the improved health behavior after the fasting cycles, and the increased self-efficacy in dealing with the desire to have children. Here is a detailed look at the key points that are particularly relevant from Salufast's perspective.
1. Feasibility and acceptance of fasting
The study emphasizes that all participants in the fasting group were able to successfully complete all three FMD cycles – despite work commitments. Several reports indicated that starting on Friday was beneficial, as days 2 and 3 of the fast are considered "crucial" and can be more easily scheduled during the weekend.
"So, I already felt like a professional. As if I knew what I was doing [...]. This made me feel more confident during the whole process."
Many found fasting with predefined box contents uncomplicated and found the fixed structure very helpful: No long recipe searches or preparation phases, just clear and easy-to-follow instructions. This is exactly where we at Salufast can build on: We ensure that our fasting box remains practical even in everyday work life, so you're not overwhelmed with extra shopping or constantly counting calories.
2. Sustainable lifestyle changes
The discussion highlights that many men significantly changed their lifestyles after the first fasting block. They report:
- greater water absorption,
- significantly reduced amounts of sugar,
- smaller portions, as the stomach volume feels like it has shrunk.
These sustainable changes are essential – even beyond the actual fasting. This is exactly what we at Salufast want to achieve with our 5-day fasting box: It serves as a "nudge" to help you question your cravings for unhealthy snacks and realize how much (or how little) your body really needs.
"I simply realized that a person does not need so much, just simply much less. [...] Because I do not need this sugar crap either."
3. Self-efficacy and motivation
For men who often feel powerless when it comes to their fertility, being able to take action is a huge step, according to the study interviews. Fasting gives them a sense of control – and this is precisely the effect we hear again and again in conversations with our clients: They experience a boost in motivation by adhering to our fasting guidelines.
"I realized how I might influence my fertility by taking action myself. That gives me a sense of control."
Moving from “I can’t do anything” to “I have it in my own hands!” not only promotes general health but may also reduce the psychological stress that often accompanies an unfulfilled desire to have children.
4. Potential improvements in semen quality
The study provides initial evidence that repeated FMD can lead to a stabilization or even slight improvement in sperm parameters, particularly in motility. While the number of participants was relatively small, the authors highlight the potential this approach could have if pursued further in larger-scale studies.
This aspect is particularly exciting for Salufast: Our Fasting Box Variation I was designed precisely to put the body into a fasting-like state, while still providing nutrients and being easy to use in everyday life. If you repeat the process regularly, the results could be even more impressive.
5. Comparison with other studies and future research needs
The study authors draw comparisons with other studies that show that intensive nutritional interventions (e.g., Mediterranean diet, calorie restriction) could have similarly positive effects on semen quality. However, FMD stands out due to the sharp calorie reduction within a clearly defined time frame (5 days).
This creates a unique selling point for Salufast: We offer a short-term fast that is both intensive and structured, which is both easy and quick to complete and quite easy to repeat.
At the same time, limitations are also identified, such as the temporary difficulties in recruitment during the COVID-19 pandemic and the short duration of follow-up. Nevertheless, this offers excellent prospects for further research. We at Salufast see ourselves as a partner who is happy to support and advance such studies.
6. Conclusions from the Salufast perspective
The points discussed in the study show that short-term fasting is relevant not only for physical but also for psychological effects – especially for men who are looking for creative and self-determined approaches to their desire to have children.
- Feasibility & suitability for everyday use : The Fastenbox Variation I can be easily implemented even if you have a full schedule.
- Sustainable dietary change : Many participants maintained a more conscious diet beyond the fasting days.
- Self-efficacy : Fasting enables men to actively work on their health and regain a sense of control.
- Potential health benefits : Initial trends indicate a stabilization or slight improvement in sperm quality.
We are pleased with the feedback from participants that the fasting phases were easy to manage and even felt (quote) more "professional" the more often they were performed. In our view, this is a strong argument for integrating FMD into daily life not just once, but regularly.
Looking ahead: Continuing research together
The authors' call for larger studies also confirms our own commitment at Salufast: We want to collect even more data in the future and give more men the opportunity to try this program. If you have any questions or are curious about what FMD feels like, we're happy to help.
If you would like to read more about the exact procedure and all the details of the researchers: Click here for the original study (Frontiers in Nutrition, 2025)
Conclusion: The discussion surrounding fasting and fertility confirms what we at Salufast experience time and again: Those who follow well-guided short-term fasting programs can not only rediscover their bodies but also experience a realization regarding nutrition, motivation, and self-efficacy. This is precisely what our Fasting Box Variation I stands for – and we are pleased that the study underscores this potential.