Are you getting nausea as well? Sounds a lot like hypoglycemia related to your recent diet change. It takes some time for the body to get used to fewer calories and sugars, and it also takes time for the body to adjust to higher fiber and more difficult to digest foods. Your body believes you are entering a fast, which can result in hypoglycemia.

Also, it can happen even if you are not diabetic.

It sounds like you definitely need more food in general and specifically more quality fats and proteins. 1200-1600 calories a day is very low for your weight, even if you're trying to lose weight. 2000-2400 is more realistic so that you don't set off a reaction in your body where it thinks it's in starvation mode. That will not only make you feel terrible, but sabotage your weight loss efforts. Also keep in mind that the quality of food is just as important as the amount. I'm not telling you to buy organic, but choose real foods, food your great-grandmother would recognize. Also, FAT IS NOT THE ENEMY. Fat can help you feel full, and stay full longer (as well as making food yummy.) Good fats include olive oil, coconut oil, butter, and lard (yes lard...it's actually mostly monounsaturated, just like olive oil.) Bad fats are crisco, margarine, soybean oil, canola, etc which your body doesn't even recognize as food. I know what I'm saying goes against the mainstream, as far as saturated fats being good for you, but it is the truth. Protein is the easy part, everyone already knows we need it. Some people trying to eat "healthy" cut out meat and go for soy, but that's the wrong direction. Soy is extremely hard to digest. You're better off eating the best quality meat and seafood you can afford for protein. There are lots of resources for more info on nutrition-westonaprice .org is a good place to start. I don't work for them or make any money from them but I'm a proud member, and I've learned so much over the years and changed my health for the better. Good luck.

As elnoa says, it sounds like your body is triggering it's fasting mode and like you're hypoglycemic.

I'm more or less in very good health, healthy weight, work out frequently, all my heart rate and blood pressure and cell counts and whatever are great.... but sometimes (more than I should ever let happen) I forget to eat or just don't because I feel busy and take medication that not only helps me get and stay motivated and organized, but also suppresses my appetite. Sometime's I'll be eating less than 600 calories a day (not good for you, do not ever do this) and man does my body let me know it. I'll be trembly, nauseous, and often fairly faint. Sometimes I actually have fainted. It'll wake me up and I'll realize "oh fuck, i forgot to eat" and I have to run/crawl to the kitchen to grab a cliff bar and water to help me feel a little better before i make a real meal for myself (hard to make a meal when you feel like you're about to faint).

The interesting thing, which you seem to be experiencing, is that you don't have to actually starve your body to set off a starvation response. For full grown woman, the baseline minimum caloric intake seems to be 1200 fairly consistently. That is a very LOW number for most people. And unfortunately, although there will be a large deficit, continuing can actually cause weight loss to slow down because your metabolism will slow to crawl. Ideally, you should gradually reduce your daily caloric intake by only a few hundred. While you do this, it would be good to begin different eating patterns, where you eat small portions of food several times a day. If you eat 5-7 tiny meals, your metabolism will be constantly active and will process the nutrients in each meal much more efficiently than if you eat the same amount in one big meal. It will also help prevent you from becoming hypoglycemic again over the course of your diet.

All of this will not only help you lose weight, but it will help you keep it off. If you want to keep weight off, you want to do it by starting dietary habits you plan on continuing for the rest of your life.

I would talk to your doctor. They would be able to help you more then any of us could. Hope you get it figured out and fixed.

Please get to a doctor you can trust, hope you're doing ok!

Back when I was 285 pounds and when I would first go on a diet I would get shaky and cranky when I lowered my calorie intake. What about having a healthy snack every two-three hours? My gastric bypass surgeon suggested for me 2 tablespoons of peanut butter spread onto a medium size banana or two crackers with 2 tablespoons peanut butter. There is also yummy healthy low fat popcorn the weight watchers brand is really good. Baked chips are another option the Yoplait yogurt is good so is the weight watchers brand yogurt. All of those are great healthy snacks that will help you loose weight but should help stop the shaking. The sugar free cookies are good they are sweetened with splenda and I can't tell the difference.

I followed Bayogirl's advice. I'm currently trying to eat 2100-2400 calories a day (recommended intake for me is 2600+), and I've stopped shaking unless I forget/feel lazy and eat 1200-1600 (like I did on Sunday).

I've lost 14 pounds since this post, but I still need to lose some weight. I hope to be a 2X again. Also, hopefully, I'll start losing two pounds max this week or so. Huge weight loss is great for the first two weeks, but anything other than that = BAD. @_@

Thanks for the advice, everyone!