I started getting serious about weight loss recently and have reduced my calorie intake somewhat significantly. I've been doing this for about 6 weeks now and the results have been very satisfying.

However, I keep having co-workers tell me that I may be losing weight too rapidly and that its "dangerous".

Just to be clear, in my case I weighed 283 lbs when I started. After 6 weeks I've lost 18 lbs. My current calorie intake is roughly 2000 a day (after counting calorie burn from mild exercise). I feel fine. The only side effect I've noticed is that I'm often sleepy at work (desk job). I eat mostly the same foods now that I've always eaten, just less of it and a complete ban on fast foods.

As I get closer to my goal of ~190 lbs I know I will have to reduce calories further to keep the same 2.5 lbs a week loss, but eventually I will bring my calorie intake back to maintenance levels.

Oddly, I don't feel hungry or anything. I'm positive I could shave off another 250 calories a day before my body started complaining, but I think my current schedule is adequate.

Am I in any real danger while following this plan? I know that losing almost 100 lbs in a year is drastic and my body will likely be affected in some way, but mostly I thought this would be good.

  • What does your diet look like and what kind of work and basic activities do you do? Because I eat way less and don't feel tired at all while programming all day long.
    – Ivo Flipse
    Commented Apr 18, 2011 at 16:18
  • I eat out almost every meal so its all restaurant food, but the menu is pretty varied (sushi, steak, salads, mexican, etc). The only physical activity I do is walk to work which about about a mile each way. I'm not really bothered by the fatigue... and if thats the worst that happens I'll be happy indeed. Commented Apr 18, 2011 at 19:28
  • 1
    As long as you don't feel like you are starving yourself you should be OK. As you further approach your goal your rate of weight loss will slow down and you will need to decrease intake or increase activity (or both) Commented Apr 18, 2011 at 20:37
  • 2
    From all the research I had been doing when I was dieting, losing 2 pounds a week average was healthy. Healthy enough that when it's all over and you stop fussing over food you may gain a tiny bit back, but will otherwise maintain your goal weight. Eventually you'll have to adjust your eating habit to brown bag your lunch once in a while.
    – Salsero69
    Commented Apr 19, 2011 at 2:10
  • 1
    The mile walk to and from the office is a good choice. It's a low heart rate workout that burns more fat than sugar. Commented May 20, 2011 at 18:13

5 Answers 5


You're losing around 10 pounds or maybe a little more per month. I've heard lots of people talk about "too rapid" of weight loss, but the truth of it is that you can easily lose 2 or 3 pounds a week, and it's not too difficult to lose closer to 5 pounds a week if you're quite a bit overweight. With an incredibly rigorous diet and moderate exercise, it's possible to achieve a loss of around a pound a day if you have enough to lose.

Extreme calorie reduction usually leads to nutrient deficiencies, and it's not advisable to do this for extended periods of time (more than 30 days really). If you are taking in healthy foods like (intact) whole grains, red meats, fresh fruits and vegetables, etc, and you aren't feeling hungry, then you are getting sufficient energy (and likely nutrient) intake. Your body will let you know when it starts becoming deficient through cravings and feelings of hunger.

Just listen to what your body tells you and typically you'll be fine. There are cases where your body's triggering mechanisms are broken, either from abuse or genetics, and your body won't tell you what it needs, so it's never a bad idea (read: always a good idea) to consult a dietitian.

  • NB Dietitian and Nutritionist have very specific meanings in the UK. nhs.uk/chq/pages/…
    – rthsyjh
    Commented Jul 15, 2014 at 13:56

Rapid weight loss itself isn't the problem. The problem is the method used to get that rapid weight loss. For example, if you starve yourself and work out like a mad man, not only will be quite lethargic, but you are going to put yourself in a state called ketonic acidosis where your body actually is burning muscles and organs rather than fat. That's the danger you want to avoid.

Any safe weight loss is going to ensure you have a proper amount of protein for your body. The minimum I would suggest is .5g protein per pound of lean body weight (i.e. how much muscle mass you have). If you have more, don't worry it just helps build up the muscle rather than maintain what you currently have. Sufficient protein alone will prevent ketonic acidosis, as you can cut out all carbs and fats and put yourself in a state called ketosis. That's a feature of a number of diets like Atkins or South Beach. Of course, you don't have to do that to lose weight. In addition to the protein, you need the proper amount of vitamins and minerals.

In my personal weight loss journey I started at 295, and 5.5 months later I was at 210. That's an average of 4.5 pounds a week. That said, my first week was a whopping 9 pound loss. I did that without feeling sluggish. I personally found that carbs caused me the most trouble with stalling weight loss--more so than fats.

To address your fatigue:

  • Eat more frequently, but smaller meals.
  • When you eat out, eat half the meal there and keep the other half for an afternoon snack.
  • Drink plenty of water (at least 2L a day). It sounds funny, but it helps me think, and it also helps with the weight loss and rebuilding muscle.

As you start cutting the calories more (as you indicated you probably will), I'd start with cutting the carbs first.

It might be helpful to measure yourself at least once a month. I've had a couple slow weight loss weeks, but have gone down in circumference. That to me is more encouraging than what the scale reads. Good luck and keep up the good work!

  • As a physician with an interest in weight loss, I find this answer to be superior to the accepted answer, whose recommendation for 2 to 5 lbs of weight loss per week is found to be potentially medically unsafe. The statement in this answer about ketoacidosis and its effect on lean body mass is consistent with what is known from the available evidence. A medically safe maximum weight loss for persons that are not losing large amounts of body water is 1 to 2 lbs per week, which is obtained by reducing daily calories to 500 kcal less that one's estimated "total daily energy expenditure."
    – scottb
    Commented Sep 9, 2017 at 15:26

This comes with the standard warning - I am not a doctor, nor do I play one on TV...

If you're simply changing portion sizes without changing the proportions of fat:carbs:protein in your diet then you could have less easily available energy which could cause some fatigue. It's not just a matter of how many calories you're getting, it also matter what form those calories are in that helps to determine your energy levels. You need a nice ratio. For higher energy I would suggest 40:40:20 protein:carbs:fat.

Since you're decreasing your food intake, you should also check to make sure that you're still getting enough nutrients. This is especially true if you're eating a lot of restaurant food, which tends to go low on nutrient rich vegetables. It might be as simple as adding a daily multivitamin. Many nutrients are important in helping your body actually process the food to get energy out of it. A simple multivitamin is probably sufficient. Anything beyond that will probably be a waste if you're not doing very high stress training and don't have any known deficiencies.

Also, while two miles of walking per day, five days per week (in addition to normal walking throughout the day) is probably adequate physical activity, I would suggest adding a bit of resistance training into the mix. It doesn't have to be anything serious, but 20 minutes of calisthenics or other light weight lifting every other day would likely improve your muscle tone and also give you additional energy.


Please don't even think of further reducing the amount of food you eat.

With the amount of speed you are loosing your weight there are chances that you'll gain it in the same speed. (body always try to recover the loss)

Go slowly and steadily you'll have better results.


I was on an approximate lose-1-pound-per-day diet two years ago. I used to eat very little and worked out a lot. I did it for about 4 months. As a result, I ended up with a heart problem and a series of neurological disorders, mostly chemical imbalances in the brain due to my hormone composition reacting strangely to my body being worn out. You have to be really careful with rapid weight loss. It can cause many more nasty things than it seems at first.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.