Intermittent Fasting Help

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Please share your favorite research-based IF resources--I need to learn more.

I started 16:8 intermittent fasting on Friday. I am 5'7", 41 years old, and have a BMI of 25. I want to try IF for the health benefits and to lose some weight. I felt great on Friday, yesterday, and most of the day today. I was less hungry in the mornings that I usually am when I eat a 600 calorie breakfast. Today I did not plan my meals well and ended up eating less protein and fat than was ideal. At about 6 pm, as I was waiting for my supper to warm up, I got very nauseated. That went away somewhat when I ate supper, but now I'm a little nauseated and very dizzy. I am not diabetic, don't have relatives who are diabetic, and my activity level today was abnormally low (I usually row fasted in the mornings for 30-45 minutes and then run around all day taking care of my family. Today all I did was drive.) Advice on how to prevent the nausea and dizziness in the future? Or what I can do about it right now?