Unintentional weight gain occurs when you put on weight without increasing your consumption of food or liquid and without decreasing your activity. This occurs when you're not trying to gain weight. It's often due to fluid retention, abnormal growths, constipation, or pregnancy.
It simply takes time. Another common reason why people report not losing weight despite reducing their calories is that they don't give it enough time. Our bodies will do their utmost to hold on to our fat reserves and you often have to be in a calorie deficit for a while before you will see any meaningful weight loss.
Undereating may cause weight gain for some people, but even if it doesn't, it's important not to eat so little that it adversely affects your health. From constipation to immune dysfunction, not eating enough can lead to a host of health issues.
For most people, there are no serious dangers involved in eating one meal a day, other than the discomforts of feeling hungry. That said, there are some risks for people with cardiovascular disease or diabetes. Eating one meal a day can increase your blood pressure and cholesterol.
Starving your body, whether consistently or inconsistently, can result in weight gain since your body is confused. Your metabolism is slowed so you're not burning through calories, or excess fat. Additionally, starving yourself can lead to fits of binge eating later, since you're so hungry.
You can't lose weight on 1200 calories a day because you're no longer in a calorie deficit. Your body has adapted to what it's been doing and plateaued. If you start your diet with a 500 calorie deficit per day, your body adapts to this in various way so that over time your energy requirements are reduced.
Lummus says that when your body goes into starvation mode, your metabolism slows to a crawl, burning calories as slowly as possible to conserve its energy stores. This is why people who cut their calories too much may reach a plateau and stop losing weight.
Your slower metabolism will slow your weight loss, even if you eat the same number of calories that helped you lose weight. When the calories you burn equal the calories you eat, you reach a plateau. To lose more weight, you need to either increase your physical activity or decrease the calories you eat.
The first stage of weight loss is when you tend to lose the most weight and begin to notice changes in your appearance and how your clothes fit. It usually happens within the first 4–6 weeks ( 1 ). Most of the weight loss in this stage comes from carb stores, protein, and water — and to a lesser extent, body fat.
Some causes may be related to stress, alcohol consumption, or medications. Other causes can be a result of health conditions like hypothyroidism or PCOS. Many causes of stomach swelling and weight gain can be treated with lifestyle changes and medications. However, others, such as ascites, can be serious.
You're holding onto water weight.
It's as simple as that really, unless you're incredibly small and in active you should and will lose weight on 1000 calories unless of course you're chronically stressed or really suck at counting calories.
Once you are an adult, your stomach pretty much remains the same size -- unless you have surgery to intentionally make it smaller. Eating less won't shrink your stomach, says Moyad, but it can help to reset your "appetite thermostat" so you won't feel as hungry, and it may be easier to stick with your eating plan.
According to many experts, eating breakfast jump starts fat burning and 5–6 small meals per day prevent your metabolism from slowing down.
The CDC state that a person can safely and effectively lose about 1–2 lb a week. Based on those numbers, in a month, a person could safely lose 4–8 lb. However, these are just estimates.
But do you really know what's realistic? Over the long term, it's smart to aim for losing 1 to 2 pounds (0.5 to 1 kilogram) a week. Generally to lose 1 to 2 pounds a week, you need to burn 500 to 1,000 calories more than you consume each day, through a lower calorie diet and regular physical activity.
“And then, of course, everybody's metabolism is slightly different. But the average weight loss that most people see on the 1200 calorie diet is about one to two pounds per week.”
However, sometimes water retention can be caused by other aspects that can be the reason behind calorie deficit but not losing weight. Salty food, high carbohydrate intake, lack of exercise and some medications can cause water weight gain even on a caloric deficit (10).
You've Gained Muscle Mass
If you're exercising regularly and doing a mix of cardio and strength training, it's very likely your body composition (ratio of muscle to fat) is changing for the better. If you're gaining muscle while losing fat, the scale may not show any weight change.