Generally when you're new to fasting, and also when you're early in a fast, you will be hungry. The hunger usually disappears after a short period however. If you ever work your way up to a 48+ hour fast, you'll see that your body finally stops complaining at that point and days 3 to 5 tend to be hunger free.
I think by skipping only a single meal each day, you're likely getting most of the hunger without many of the benefits. With only breakfast skipped, your metabolic state may be closer to a calorie-restriction diet (which can reduce your resting metabolism) than a fasting one. Brain-fuzziness and sluggishness are usually a symptom of eating, not fasting.
A few tips:
- Skipping only breakfast might be a good start for you, but to maximize weight loss (or theraputic fasting) goals, you'll probably want to work your way up to one long fast per week (e.g., 23 hrs or more) and one or two 16 to 18 hour fasts. As you get better at fasting, you'll look forward to it.
- Depending on how much carbohydrate you have in your body you won't reach ketosis (fat burning, assuming that's your goal) until 18 to 24 hours into the fast. If you eat a typical Western/US diet, you may need a full 24 hours to break into ketosis. If you eat a high-fat/low-carb or keto diet, which I recommend, you will likely reach ketosis in half that time or less, which translates to more fat loss.
- A pound of body fat is 3,500 calories. Assuming a 2,500 calorie per day metabolism, you can lose around .5 lb each 24 hour fast, plus some water weight (the latter of which returns quickly after the fast, so don't get too excited).
- I've found it helpful to stay active during a fast. Go for a walk or hike. Get a workout in. It helps clear your mind particularly if you're hungry.
- If you become ravenous and your brain gets panicky from the hunger, listen to your body and either break the fast or have a cup of broth to see if that helps you get over the hump.
Some benefits of 18+ hour fasts-
- Autophagy / cell-repair, where your cells perform some Spring Cleaning and burn away the junk that has accumulated in the cell's attic and basement.
- Reduction in insulin levels. This can help with Type 2 diabetes, and it allows fat burning to take place (your body won't burn body fat while carbs are available in your system).
- Surge in growth hormones. During a long fast you can experience a 2000% increase in growth hormones. This is why the body-builders are into keto/IF -- they're focused on eliminating as much fat as possible and building muscle.
Some links:
What is Intermittent Fasting? Dr. Jason Fung Part I https://www.youtube.com/watch?v=VIhhrYjVhOk
How to Maximize Fat Burning, Dr. Jason Fung Part II https://www.youtube.com/watch?v=nwE4D8Xe8JA
The Sweet Spot for Intermittent Fasting https://medium.com/the-mission/the-sweet-spot-for-intermitte...
(The Failure of) 'The Biggest Loser' Diet – Explained https://idmprogram.com/biggest-loser-diet-explained/
If you have more questions, maybe might try this subreddit: https://www.reddit.com/r/intermittentfasting/