Jeremy Barnes, professor of health promotion at Southeast Missouri State University, replies.
Body weight depends on a multitude of factors, and, as you might imagine, both lifestyle and genetics play critical roles. The key to weight control is balancing energy intake with energy expenditure, a relationship that is often referred to as the energy balance equation.
Energy input comes from the food and drink we consume and is usually measured in kilocalories (kcal). The U.S. Department of Agriculture assigns calorie levels based on an individual's sex, age and activity level. The intake quantities range from 3,000 kcal for active males between 19 and 20 years of age to 2,000 kcal for sedentary males 76 and up. (The corresponding numbers for females are 2,400 kcal and 1,600 kcal, respectively.) When energy intake is greater than energy expenditure the body will store excess energy as fat, regardless of whether those excess kcals came from fat, carbohydrate, protein or even alcohol.
Energy expenditure consists of three components: resting metabolic rate (BMR), which is the energy your body uses to maintain normal function throughout the day; diet induced thermogenesis (DIT), the energy needed to digest, absorb, transport, metabolize and store food and drink; and physical activity. In the sedentary individual BMR typically accounts for 60 to 75 percent of energy expenditure, DIT is responsible for about 10 percent and physical activity between 10 and 25 percent. (As you might expect, active individuals will have a greater proportion of energy expenditure accounted for by physical activity.) Our bodies are expending energy all the time. Even while asleep the body requires energy to fuel the multitude of complex functions required to keep us alive.
Since one pound of body fat is equivalent to about 3,500 kcal of energy, the energy balance equation suggests that an increase in food intake or a decrease in energy expenditure equal to 3,500 kcal will result in a weight gain of one pound. Conversely, a weight loss of one pound will result for every 3,500 kcal worth of food not eaten or an equal amount of increased expenditure. Although this is a good rule of thumb for predicting either weight gain or loss, there are considerable individual differences that the energy balance equation does not account for. Weight change is a relatively slow process—taking place over longer periods than just mere minutes, hours or days. Weight gain, for instance, involves a long-term state where caloric intake exceeds expenditure.
And thus the answer to a question like the one posed here cannot really be answered unless we know all the other aspects of an individual's lifestyle. It is true to say that had someone gone for a brisk walk rather than, say, taking an afternoon nap, they would have utilized more energy for the duration of the walk.
Sleeping itself, however, is not the cause of weight gain. As we have seen above, the key is really energy balance over extended periods of time. Unfortunately, in the U.S. many people are consuming more energy than their bodies can use (or than they are using), which has led to a situation of epidemic proportions where over one third of all adults are now obese.
Interestingly, there have been a few recent studies indicating that individuals who either suffer from sleep deprivation or get only limited amounts of sleep may be more susceptible to weight gain than those who get adequate sleep. It appears that lack of sleep leads to decreased release of the hormone leptin—higher levels of which confer a feeling of fullness, whereas low levels can result in feelings of hunger. In addition, sleep loss increases levels of the hormone grehlin, which also makes people feel more hungry.
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4 Comments
Add CommentIts true human body always needs a multidimentional approach. sleep, genetics, lifestyle, stress attititude and many more factors are there to decide the put on and off. But still the sleeping after meals surely not causes any loss of weight. As per ayurveda such pattern of sleep vitiates Kapha dosha . DR SHRIRANG GALGALI MD AYURVEDA
Reply | Report Abuse | Link to thisI have heard from numerous sources that eating after 8pm leads to immediate storage of those calories as fat, since the body's metabolism slows during sleep and does not burn them. And that eating refined grains (e.g., typical white bread or pasta) leads to weight gain because the calories are metabolised so quickly (compared to whole grains/complex carbs) that unless you immediately exercise you dont burn those calories and so store them as fat. I've also heard that after a workout (like weight lifting), one should eat some protein immediately to assist muscles in rebuilding and repair, or building muscles is difficult (especially for women). I would love to know if these statements are true. I've always thought that the caloric intake/expenditure leading to weight gain or loss must be calculated over a period of days, not hours. Is anyone aware of high-quality research to confirm or refute the statements above? Thanks.
Reply | Report Abuse | Link to thisI am desperately trying to figure out how it is that I gained a pound while I slept last night.
Reply | Report Abuse | Link to thisI did not eat for 5 hours before going to bed. I weighed myself twice before bed and twice after waking up, and someone I gained a pound while I was sleeping.
Now when you consider that I urinated a good amount when I woke up BEFORE I weighed myself in the morning, one would assume that I would have lost weight just from the water/urine.
What the heck is going on here?
You can see my whole story here:
http://thinjohn.com/blog/being-fat/how-can-you-gain-weight-while-you-sleep/#respond
it is my personal weight loss blog.
I am obese and trying hard to lose weight, so if I am gaining weight while I sleep, this is a pretty big deal.
Weight management is more than just the numbers on your scale. It is normal for weight to fluctuate up and down on a daily basis, even by as much as 5+ pounds or more depending on the individual and what you ate.
Reply | Report Abuse | Link to thisWhy are you seeing this 1 pound gain ? It's not 1 pound of fat you are seeing, but probably water weight. What did you eat previous night ? Are you well hydrated enough ? (drinking water) ? This could very well be water pretension weight, stools, etc... As you wake up in the morning, you will go to the bathroom initially, but you may go again to urinate or get a few bowel movements - you will see as the day progress the weight comes down. If you are retaining water or have stools in reserve, eventually as they get flushed out over days the weight will balance out and adjust. Don't take your weight on a daily basis but over time - and don't be scared of small variations - these variations can be quite big at times. Some medication / medical conditions can cause rapid weight gain - For women, during menstrual cycle body retains water so you can see a few pounds gain - eating a salty meal, etc, give it a few days for your body to flush this excess water from your system and you should be fine. If you are not getting regular bowel movements, constipated, bloated, gas, etc, this can add some pounds to your scale as well.