My mother always told me that eating after sundown would result in
obesity because the body doesn't have the opportunity to "burn up" the
calories, and they turn directly into fat. I never really investigated
the matter until now, but it seems that this advice was not based upon
fat ...er, not based upon fact. I've gathered some info on this
weighty subject for you.
"When total calories are kept constant, does eating at night (whether
just before bed or in the middle of the night) lead to weight gain?...
A 1997 review article summarizing the results of past research
concluded that meal frequency - whether during the day or at night -
had no clear effect on body weight. That is, people who chose to eat
frequently, regardless of the time of day, had no higher rate of
obesity than those who ate fewer large meals.
In a study of more than 2,000 middle-aged men and women, 9% of women
and 7.4% of men described 'getting up at night to eat.' Overall, there
was no difference in weight gain between those who did and those who
did not. A study in 2004 of more than 800 men and women noted that the
more people ate in the morning, the less they tended to eat during the
course of a day, while people who ate more at night tended to eat more
overall. A trial from January 2005 found that eating late at night was
not associated with weight gain even among people with 'night eating
It is possible that, for some people, eating at night is associated
with weight gain. Perhaps they find it easier to be careful about
portion size and food choices during the day but simply 'lose it' at
day's end. For some, the structure of three meals a day may make it
easier to avoid excessive calorie intake. But it's probably a myth
that eating before bed has a unique ability to promote weight gain
compared with eating at other times of the day. Although scientific
studies someday may prove that calories ingested before bed are
handled differently than calories ingested at other times, evidence
for this commonly held belief is lacking. For now, it's safe to assume
that one's weight reflects the balance between calories burned and
calories consumed over time, regardless of when you choose to eat."
InteliHealth: Does Nighttime Noshing Make You Fat?
"Myth: Eating after 8 p.m. causes weight gain.
Fact: It does not matter what time of day you eat. It is what and how
much you eat and how much physical activity you do during the whole
day that determines whether you gain, lose, or maintain your weight.
No matter when you eat, your body will store extra calories as fat."
NIDDK (National Institutes of Health): Weight-loss and Nutrition Myths
"Breakfast like a king, lunch like a prince, dinner like a pauper' -
is there any truth to this?
[Dietitian Dr Trent Watson] sets the record straight: "It's the total
energy you eat throughout the day that's important. You can eat all
your daily kilojoules after 6pm, and you won't gain any more weight
than if you ate it earlier in the day. Weight gain occurs when you
consume more energy than you expend."
The Daily Telegraph: Top 10 food myths busted
"Subjects who eat late in the evening may increase the amount of
glucose stored in muscle as glycogen. In humans, muscle glycogen
fluctuates in accordance with periods of muscle activity and
subsequent carbohydrate consumption. Data suggest that the consumption
of carbohydrate-rich foods in the late evening leads to increased
glycogen levels in the muscles. Unless this stored glycogen is burned
as fuel, it will ultimately be stored as fat. Therefore, consumption
of late-evening meals with carbohydrate-rich foods may also be related
to obesity through its effect on hormonal regulation of energy and
lipid metabolism. However, we found that the interval of time between
the last episode of eating and the time to bed was not associated with
the risk of obesity. Further investigation is warranted to examine the
association of this interval, as well as the nutrient composition
(i.e., percentage of calories from carbohydrate) of the last eating
episode, with obesity."
American Journal of Epidemiology: Association between Eating Patterns
and Obesity in a Free-living US Adult Population
"The purpose of this study was to determine whether meal ingestion
pattern [large morning meals (AM) vs. large evening meals (PM)]
affects changes in body weight, body composition or energy utilization
during weight loss. Ten women completed a metabolic ward study of 3-wk
weight stabilization followed by 12 wk of weight loss with a
moderately energy restricted diet [mean energy intake ± SD = 107 ± 6
kJ/(kg·d)] and regular exercise. The weight loss phase was divided
into two 6-wk periods. During period 1, 70% of daily energy intake was
taken as two meals in the AM (n = 4) or in the PM (n = 6). Subjects
crossed over to the alternate meal time in period 2. Both weight loss
and fat-free mass loss were greater with the AM than the PM meal
pattern: 3.90 ± 0.19 vs. 3.27 ± 0.26 kg/6 wk, P < 0.05, and 1.28 ±
0.14 vs. 0.25 ± 0.16 kg/6 wk, P < 0.001, respectively. Change in fat
mass and loss of body energy were affected by order of meal pattern
ingestion. The PM pattern resulted in greater loss of fat mass in
period 1 (P < 0.01) but not in period 2. Likewise, resting
mid-afternoon fat oxidation rate was higher with the PM pattern in
period 1 (P < 0.05) but not in period 2, corresponding with the fat
mass changes. To conclude, ingestion of larger AM meals resulted in
slightly greater weight loss, but ingestion of larger PM meals
resulted in better maintenance of fat-free mass. Thus, incorporation
of larger PM meals in a weight loss regimen may be important in
minimizing the loss of fat-free mass."
The Journal of Nutrition: Weight Loss is Greater with Consumption of
Large Morning Meals and Fat-Free Mass Is Preserved with Large Evening
Meals in Women on a Controlled Weight Reduction Regimen
So it appears that for most of us there's nothing wrong with eating at
night, as long as the entire day's calorie count is appropriate.
However, there may be health risks associated with nighttime eating
for people who have GERD (gastroesophageal reflux disease) and/or
"Compared to nonasthmatics, asthmatics have significantly more
frequent and more severe day and night GER symptoms and significantly
more of the pulmonary symptoms (nocturnal suffocation, cough, or
wheezing) so often attributed to GER. The habit of eating before
bedtime appears in asthmatics to have serious and life-threatening
American Journal of Gastroenterology: Asthmatics have more nocturnal
gasping and reflux symptoms than nonasthmatics, and they are related
to bedtime eating.
Thanks for an interesting question! Please let me know if anything is
in need of clarification; I'll gladly offer further assistance before
you rate my answer.