I’ve been on OMAD 20/4 fast for about 7 days now. Surprised at how easy it has been. I’ve not been too active this week, and if life were normal I’d probably be hungrier since I’d be moving more. I’m on keto for fat loss, and started fasting since I have not seen any real fat loss on the diet so took to next level. I break my fast with some kind of fatty snack and have dinner later. I’m sort of worried about slowing my metabolism too much. My one meal is not massive, just until satisfied. Am I eating too little? Not sure about cycling on and off fast days.
Keep in mind that fuel can come from your plate or from your stored fat. For most, hunger is the primary signal you’re eating too little and/or drawing too little from fat stores for your energy expenditures. If you ignore the hunger signal long enough (and your mileage will vary) then your body has only two ways to cope with insufficient fuel. The first is to make you feel tired, listless, cold, weak, dull, apathetic etc to make you less active so you burn less fuel. The second is to throttle down all the autonomic processes running in the background to slow your overall metabolism and use less fuel.
If you restrict overall calories or fast long enough to get to the first stage, that’s your office memo to eat more. If you don’t get the memo, you will soon progress to the second stage, taking out some lean mass, muscle, cartilage, collagen, bone, etc in the process. The second stage will take out even more lean mass and result in serious long term metabolic slowdown which will not come back any time soon. The Big Losers study showed metabolic slowdown of 500 kcal per day for 5 years after the dieting ended. You don’t want to go there.
Heart palpitations finally got the better of me
As there is no info about your needs vs your meal, who knows?
OMAD alone is fine but undereating is a problem indeed. If you can’t enough eat for one meal, don’t do OMAD. I realized I can’t have my usual sized meals on OMAD, they shrunk so I underate. OMAD/TMAD mix is better for me but I love eating and having lunch with my SO so I rarely do OMAD. But it would be ideal on some days and definitely not every day…
Eating until satiated is fine but do you get hungry later or not? I almost always get at least a tiny big hungry or weak if I had too little food for the day so I notice if there is a problem. “Easy” says little to me as some people find tiny hunger easy. I always eat when I am hungry, no matter how subtly as hunger annoys me, it just won’t do. I don’t necessarily get a stronger hunger even if I undereat, tiny hunger is a useful warning.
Exercise may complicate things. It makes my deficit bigger and I couldn’t do a long (for me) cycling with OMAD, I just couldn’t eat enough on keto for that. But some people can eat really huge meals on OMAD too.