|Beans and lentils are a major part of my diet|
Energy in = Energy out
This simple equation explains why I cannot eat only one meal per day at the moment. When I was eating only one meal per day, I had a sedentary job and was doing only about 20 minutes of body-weight exercises per day. Now on the other hand I lift heavy 6 days a week and ride my bike about 40 minutes and swim in an ice-cold lake every day. This, and the goal of gaining muscle requires me to eat a lot more on a daily basis. If you are not interested in either a lot of daily activity nor in gaining any weight, then OMAD is probably the best diet for you to gain maximum longevity- and health-benefits.
Lowered digestive capacity
For many years I struggled with crohns disease and still do to some extend. Which means that I have to be very careful not to eat any foods that trigger a bad reaction in me. That shows me that my digestive capacity and the robustness of my digestive system is lower than in other people. I have found out that it is better for me to eat a meal that is below my digestive capacity, which means smaller portion sizes. It takes me unusually long to digest large meals and this shortens the fasting part of the OMAD approach which is the whole point of doing it.
Constant muscle twitches with a high fat diet
In my experience the OMAD approach is better suited for a relatively high-fat diet. I tried out a low-fat approach, but is was absolutely impossible to eat enough calories that way. Eating a diet high in fat though is perfect for intermittent fasting. While fasting you utilize mainly fat for energy and therefore eating a high-fat meal allows the body to efficiently use that fuel. Switching back and forth between carbohydrate- and fat-metabolism gives many people a feeling of low energy.
I had the additional problem that my muscles would start to twitch all over my body when I ate a high fat diet. I have tried many different things to solve this, but have not found a solution. The only thing that stopped it was going back to a mainly carbohydrate based diet, which is better suited for eating several meals per day.
I actually figured this problem out. You can read about it here.
What I do now
I adopted a flexible approach to fasting. I like the feeling of fasting. Therefore I do about one 24 hour and two 16-18h fast-days per week. I closely monitor my weight though and if I do not see a slow but steady increase in my weight of about 1 kg per month I will have to reduce that even further.
I also switched away from the high fat approach back to a high carb diet. My diet is about 70% of calories from carbs, 15% from protein and fat. Some days my fat intake might be around 20-25% though.
I am still eating whole plant foods, but I have also found that I need some fatty foods like nuts and seeds in my meals in order to feel satisfied.