Better to Exercise Before or After Meals for Weight Loss and Blood Sugar Control?
“Better to Work Out Before or After Meals
for Weight Loss and Blood Sugar Control?” A systematic review and
meta-analysis on exercise timing for fat metabolism found
that exercising in a completely fasted
the state may work best. The Japanese team that published
some of the seminal work in this area went
as far as to assert: “If exercise were
a pill to burn body fat, it would be effective only
when taken before breakfast.” Surveys show few people exercise before breakfast, though. Before asking people
to make the switch, we need to make sure that these
tantalizing 24-hour results translate into weight loss
over the long term. There’s a solid theoretical basis,
but you don’t know until… you put it to the test. In a study of experimental
weight gain, volunteers were fed up to
4,500 calories a day for six weeks while vigorously exercising
a total of 300 minutes a week, either always after an overnight
fast or after a meal. A control group who didn’t exercise
at all gained about 6.5 pounds, compared to 3 pounds in the
exercise-after-a-meal group.
The pre-meal exercise group
worked out the same amount, but only gained about half
as much—1 3/4 pounds. What about weight loss, though? Twenty young women
were randomized into three hours
a week of before or after a meal exercise. Same diets, the same
amount of exercise, and… disappointingly, about
the same amount of weight loss. The pre-meal exercise group
did lose about an extra pound of body fat (total weight loss
3.5 lbs. vs. 2.2 lbs.), but this did not reach
statistical significance, meaning such a small
difference could very well have been due to chance. A study of six weeks
of low-volume, high-intensity interval training
before or after meals similarly failed
to show a difference. One explanation that’s
been offered for this failure is that the increased fat loss
during premeal exercise might be “neutralized”
by the lesser diet-induced thermogenesis. In other words, it costs
our body fewer calories to process food if we eat after
compared to before physical activity. When we exercise after a meal
our body gets mixed signals. Exercise is all about mobilizing
energy stores for fuel, whereas eating is more about
assimilation and storage, and the metabolic
challenge presented by the ensuing
“hormonal tug-of-war” might be responsible for the 15
to 40 percent greater calorie cost.
This has led some
to recommend exercising after meals to facilitate
weight loss. If you do the math, though,
our body is so efficient at digesting that the 15 percent
to 40 percent increase might only come out
to be 3 to 12 calories. Such a slight difference
would be easily overwhelmed by the huge disparity in fat loss, as confirmed by the 24-hour
fat balance studies, showing up to 500 calories
of fat-burning difference. I would suggest
a more reasonable explanation might
be that the clear body fat deficit on pre-meal
exercise days are made up for by extra fat
storage on non-exercise days. Your body likes to hold on
to extra body fat if it can, and so on days
you’re not driving it down it may try to even things out.
Both of the failed
weight loss studies had people exercising
only three days a week, so, their bodies had most
of the week to compensate. The study I’d like
to see is a pre-meal vs. post-meal exercise on all or at least most days
of the week to see if we can continue
to drive down fat stores. For those with diabetes, though,
you’d want to do the opposite. You can imagine how
the siphoning effect muscles have on excess blood
sugar during exercise might be great for those suffering from elevated blood sugar. And indeed, exercising
after a meal can bring down blood sugars as well as some blood
sugar-lowering drugs. Randomize type 2 diabetics
to a 20-minute stroll (about 2 mph) before dinner
versus after dinner, and the after-dinner
group blunted their blood sugar
spike by 30 percent.
Same meal, same amount
of exercise, but a significant effect
on blood sugar control thanks to a little
tactical timing. Even just a 10-minute walk after a meal may
make a difference. So, for those with
blood sugar problems, it’s better to exercise
after meals than before them. Blood sugar from a meal starts
appearing in the bloodstream for 15 to 20 minutes
after the first bite and is ramping
up by 30 minutes to peak at around
the one-hour mark before declining to premeal
levels within a few hours. So, for optimal
blood sugar control, prediabetics, and diabetics
should start exercising 30 minutes after
the start of a meal and ideally go for an hour to completely straddle
the blood sugar peak. If you had to choose a single
meal to exercise after, it would be dinner,
due to the circadian rhythm of blood sugar control
that wanes throughout the day. Ideally, then, breakfast would be
the largest meal of the day and you’d exercise after that,
or exercise after every meal.
https://is.gd/cgc_9_8_prescreen_submission
My 6-step formula for GCSE exam success. Achieve a top grade in all your GCSE exams whilst spending half of your time doing the things you enjoy. I explain why note-taking is NOT the way ➯➱ ➫ ➪➬ The General Certificate of Secondary Education (GCSE) is an academic qualification in a particular subject, taken in England, Wales, and Northern Ireland. State schools in Scotland use the Scottish Qualifications Certificate instead. Private schools in Scotland may choose to use GCSEs from England.
