If I cosume only 700calories/day will it affect my health?

700?!?! I can burn that during a good trip to the bathroom. I'm well over that by lunchtime. How are you even upright?

My breakfast was almost 700 calories

jzammetti nailed it. The most immediate down side of sever calorie restriction is that your body will selectively hold onto fat tissue, and will instead burn muscle tissue to make up for the difference between caloric intake and the requirements of your organs and regular body functions. So while the *weight* will come off fast, your overall body fat % isn't going to shift as much as it would if you fuel yourself with a balanced diet. At the end of the day the goal is to lose *fat* not just pounds, for that you need to be eating enough calories to fuel your body, while maintaining a slight deficit and doing strength training and other exercises to maintain lean muscle tissue.

Long term, sever calorie restriction can cause organ damage. The effect of the body burning muscle tissue for fuel applies to your heart -> can cause serious heart related complication in addition to a myriad of other things.

I'd recommend checking out Fat 2 Fit radio's pod casts, and nerdfitness.com. Both sites have a lot of information about how to set goals to achieve fitness, health and body composition goals. At the end of the day, the important thing is to be strong and healthy. Starving yourself isn't the way to get there.

what are your recommendations

Eat more.

I don't want to alarm you but this is very dangerous. You could be setting yourself up for an eating disorder. That is the worst case scenario, if that doesn't sound serious you must not be aware of all the implications. It will not only impact your physical health, but it is a mental health issue as well a serious one.

Best case scenario, you lose the weight. Which it sounds like you don't have much to lose maybe 30 lbs. But, you have no idea now how to eat healthy how to add calories back in. Your body is angry now because you have been starving for several months. You have lost muscle tone, your metabolism is in the crapper. You may have issues with depression now, because you body is going to want to slow down to conserve calories and that will effect your mental health. But, since you have lost the weight you are motivated enough to see a doctor and get your health back on track, it will probably take a year or more, you most likely will not be able to do it, but you are highly motivated and you add calories back slowly and you learn to eat healthy and exercise and maybe that loose skin starts to firm up a bit. But, most likely you will gain everything back, bodies have a way of making you do things that you would really rather not do. The drive to eat is primal.

So since it will take a year or more to fix your health if you haven't done any permanent damage, why not take the time to do it right. If you have 34 lbs to lose 68 tops, then what is the rush. You aren't morbidly obese. You might not even be obese at your height. So, just being overweight not a huge deal. Most people in this country are 66% according to most sources. You are one of the lucky ones as a matter of fact. You can take control of your diet and your health now before developing serious issues like diabetes and heart disease. Shoot for one pound a week, two at the most. It's very doable, it doesn't have to be all that painful. But, you will have to make changes and gradual is better and will be much less a strain emotionally.

Add some fiber to your diet. Get a bit of exercise like an hour a day or at least a half hour. Cut out processed foods gradually and replace them with a homemade versions provided the home version is actually healthier. Switch from white potato french fries to sweet potato ones for one example of a healthier switch. Drink more water or herbal tea. But, what ever you do don't do anything drastic. Bodies don't like drastic measures.

As far as the "I can regain the muscle later" comment-- it's a lot harder to build muscle than I think you realize. It's much easier (and better IMO) to hold on to the muscle you have while you lose fat.

I have did this and lost 24 lbs since 1/1/13, but I have no energy (I LOVE lifting weights). I am supposed to eat 1860 calories a day, but lowered it to 1700 with 400-650 a day of aerobics. I suffered the next day when I realized I ate only 1200 calories the previous day and did 500+ calories of exercise.

Instead of going to the gym or the 2nd 40 minute walk with the Lab at home, I dozed off on the couch after work. By 8pm I was in bed.

I've been losing about 1kg a week for the last 2 months n I feel grate. But I've just realised I havent had a period for the last 2 months, im definitely not pregnant so could this b down to my diet? I average about 700 calories a day.

Problems with extremely low calorie intake (most of this stuff doesn't happen right away, but later down the road...its kind of like how some smokers end up with emphysema or lung cancer and some don't):

- Malnutrition

"Inadequate caloric intake can lead to malnutrition over time. According to MedlinePlus, malnutrition occurs when the diet does not allow the intake of a sufficient amount of nutrients. A diet with extremely low calories does not allow for adequate consumption of the vitamins, minerals and antioxidants the body needs to perform its daily life processes. Vitamin deficiencies can lead to various problems, including fatigue, impaired wound healing and extreme weight loss." *1*

- Slower Metabolism (takes a while, but does happen)

"Metabolism is the rate at which the body burns fuel for energy. The basal metabolic rate is the minimum number of calories necessary to perform daily basic functions such as breathing, growth, cellular repair and digestion, according to MayoClinic.com. When calories are restricted over a long period of time, the body will compensate by holding on to the few calories that are consumed. Instead of burning calories freely, the body will perform basic life processes more slowly to conserve fuel. This can actually lead to weight gain." *1*

- Physical Changes

"A decrease in caloric intake may cause positive physical changes at first, especially in individuals with extra weight to lose. However, an extreme decrease in caloric intake can cause negative physical changes over time. Once individuals lose excess weight, calorie restriction can cause various physical problems. The Calorie Restriction Society indicates that decreasing daily calories too much can lead to reduced bone mass, fatigue, sensitivity to cold temperatures and food obsession due to extreme hunger. The CRS recommends gradual calorie reduction over a period of at least six months to avoid some of the side effects of low caloric intake." *1*

-Side Effects:

"Let’s look at some of the uncomfortable side effects of very low calorie diets:

Dry mouth
Headache
Dizziness
Fatigue and weakness
Cold intolerance
Dry skin and nails
Menstrual irregularities in women
Hair loss
Constipation/diarrhoea
Irritability and confusion
Inability to concentrate
Muscle breakdown
Problems with nerve and muscle function due to an imbalance in minerals and electrolytes
Conditions such as osteoporosis, anaemia, gout, gallstones, clinical depression, heart problems, renal failure, and liver disease" *2*



References:
*1*
http://www.livestrong.com/article/277053-what-are-the-dangers-of-low-caloric-intake/
*2*
http://www.dietriffic.com/2009/05/14/very-low-calorie-diet/