The 6 Weight-Loss Tips That Science Actually Knows It Work.
Some of the weight loss articles out there these days are
getting a little nutty. New scientific studies that shed light on how
metabolism works are wonderful and valuable in their own right, but when
findings get morphed into magical new “tips” for losing weight, something’s
amiss. Some recent pieces in prestigious journals, which have sought to dispel
the myths of weight loss and of the individual diets themselves, suggest that
the medical community is also getting tired of the hype and the unfounded
assumptions that permeate the public discussion.
When it comes down to it, the things we know to be true
about weight loss are relatively simple, and certainly few. They’re also
extremely effective when actually carried out. So, from the researchers who
have studied this stuff for decades, here’s pretty much everything we know
about weight loss today, whittled down to six points about how the body
actually gains, loses, and maintains its weight.
1. Dieting trumps exercising
We hear a lot that a little exercise is the key to weight
loss – that taking the stairs instead of the elevator will make a difference,
for instance. But in fact it’s much more efficient to cut calories, says Samuel
Klein, MD at Washington University’s School of Medicine. “Decreasing food
intake is much more effective than increasing physical activity to achieve
weight loss. If you want to achieve a 300 kcal energy deficit you can run in
the park for 3 miles or not eat 2 ounces of potato chips.” It’s as simple as
that. Some studies have borne out this dichotomy, pitting exercise against diet
and finding that participants tend to lose more weight by dieting alone than by
exercise alone. Of course, both together would be even better.
The problem is that when you rely on exercise alone, it
often backfires, for a couple of reasons. This is partly because of exercise’s
effects on the hunger and appetite hormones, which make you feel noticeably
hungrier after exercise. “If you walk briskly for an hour and burn 400 kcal,”
says Klein, “and then have a beer and a slice of pizza afterwards because the
exercise made you feel hungry…you will eat more calories than you have burned.”
It may not always be beer and pizza, but people do tend to naturally compensate
for the calories they expend.
“This is an adaptive system,” adds David Allison, PhD. “For
every action there’s a reaction; that’s a law of physics, not of biology, but
it seems that it also works in biological systems. This is why we often
overestimate quite radically an effect of a particular treatment.” He points out
that public health campaigns that, for example, urge people to take the stairs
instead of the elevator or go on a nightly stroll – or, for that matter, even
eat fewer calories – are unlikely to work, since they may fail to take into
account the body’s compensatory mechanisms that can totally counteract the
effect.
The other problem with exercise-without-dieting is that it’s
simply tiring, and again, the body will compensate. “If the exercise made you
tired so that you become more sedentary the rest of the day, you might not
experience any net negative energy,” says Klein. Some of the calories we burn
come from our basic movements throughout the day – so if you’re wiped out after
exercise, and more likely to sit on the couch afterwards, you’ve lost the energy
deficit you gained from your jog.
2. Exercise can help fix a “broken” metabolism, especially
during maintenance
“People used to come into the doctor’s office and say, ‘My
metabolism is broken!’” says James Hill, PhD, at the University of Colorado.
“We never had any evidence that it actually was, until recently. We were wrong
– it was!” While exercise may not be as important for weigh loss as calorie
restriction, as Hill says, it’s important in another way: It begins to repair a
broken metabolism.
“A lot of what we know in this area comes from NASA, of the
bed-rest studies,” he says. “Within a couple of days of non-activity, the
metabolism becomes inflexible. You start moving again, and it does start to
change.” Your metabolism may not ever go back to “normal” (more on this below),
but the evidence indicates that it can indeed pick up again, in large part
through moving your body every day.
This is a large part of why exercise is critical in the
maintenance phase, which is well known to be more difficult than the weight
loss phase. Essentially, it buys us some wiggle room, says Michael Jensen, MD
at the Mayo Clinic. “Exercise is very, very important for maintaining lost
weight, and people who are not physically active are more likely to gain
weight. We think it’s partly because in the extra calories burned from physical
activity, you have a bit more flexibility in food intake, so you’re not so much
relying on ridged changes in eating habits; it makes it more tolerable.”
3. You’re going to have to work harder than other people –
possibly forever
Though exercise can help correct a metabolism that’s been
out of whack for a long time, the grisly reality is that it may not ever go
back to what it was before you gained weight. So if you’ve been overweight or
obese and you lose weight, maintaining that loss means you’re probably going to
have to work harder than other people, maybe for good. “The sad thing,” says
Hill, “is that once you’ve been obese or not moving for some time, it takes a
little more exercise to maintain. It doesn’t come back to normal.” It’s not a
pretty reality to face, but coming to grips with it is important, he says, so
that you won’t get frustrated when you discover that you have to do more work
over the long term than your friend who was never overweight.
Building muscle can help your body burn a few more calories
throughout the day, but it’s also likely that you’ll have to work harder
aerobically in the long run. “It’s not fair, but that’s the way it is,” adds
Hill. “Once you understand it, though, you know it and it’s better. Because you
can work with it.”
4. There’s no magical combination of foods
We often think that if we can just discover the “right”
combination of foods, we’ll magically lose weight or maintain what we’ve lost.
There are low-fat diets, low-carb diets, low glycemic diets, Paleo diets, and a
lot of iterations of all of these. Jensen points out that in fact there doesn’t
seem to be any “right” diet, and there doesn’t seem to be any evidence that one
particular diet will work better with an individual’s specific metabolism. “The
big myth out there,” he says, “is that there’s a magical combination of foods –
be it protein, vegetarian, and what have you – that’s going to be unique
because of its unique interaction with your metabolism. We know pretty much
that any diet will help you lose weight if you follow it. There’s no magic
diet. The truth is that ALL Diets will work if you follow them.”
5. A calorie IS a calorie!
And for energy balance, it’s the number of calories that
matters. Weight loss on the Twinkie Diet proves this principle: Last year, Mark
Haub at Kansas State University lost 27 pounds eating junk food. And this is
pretty good proof of concept, says Yale University’s David Katz, MD, who has
written extensively on the futility of the “is a calorie a calorie?” debate.
It’s certainly true – at least in theory and sometimes in
practice – that all calories are created equal. “From the standpoint of body
weight,” adds Marion Nestle, PhD, of NYU, “a calorie is a calorie no matter
what it comes from. You can gain weight eating too much healthy food as well as
unhealthy. From the standpoint of health, it’s better to eat your veggies….
It’s just a lot easier to overeat calories from junk food than healthy food.
But it can be done.”
But the source of calories obviously matters for other
reasons. One, says Katz, is that “the quality of calories is a major
determinant of the quantity we ingest under real world conditions.” First of
all, no one overeats veggies, so on a practical level, that’s a non-issue. “But
where the calories come from does matter in that they influence satiety,” he
adds, and this is partly psychology and partly biology. In fact, the food
industry has carved out a whole new area of food science to study the “bliss
point,” in which foods are created to increase the amount it takes to feel
satiated and full. On one hand, says Katz, “we have the ‘bliss point’ science
to tell us that the food industry can process foods to increase the calories it
takes to reach satisfaction. We have the reciprocal body of work, including the
Harvard study of the ONQI, showing that ‘more nutritious’ means, among other
things, the opportunity to fill up on fewer calories.”
It’s true that types of foods you eat may, over time, affect
your metabolic profile, so they may also matter in this way, but when it boils
down, sticking to anyreduced-calorie diet will create the energy deficit needed
to lose weight. So the point is not to question what a calorie is, but rather
to understand that we need to “trade up” our foods, says Katz – exchange the
very dense, calorie-packed foods for foods that are less calorie-dense and more
nutritionally dense: these are the ones that are bulkier, less energetically
rich, have more or higher quality protein, are lower on the glycemic index, and
more fibrous.
6. It’s all about the brain
As my colleagues have reported, when it comes down to it,
it’s not the body or the metabolism that are actually creating overweight or
obesity – it’s the brain. We all know intuitively that poor decisions are what
make you gain weight and better ones are what make you lose it. The problem is
that over time, the poor decisions lead to significant changes in how the brain
governs – and, amazingly, responds to – the hunger and satiation processes.
Years of any kind of behavior pattern lay down neural tracks, and overeating is
no exception.
The good news is that there’s increasing evidence that the
brain can, in large part, “fix” itself once new behavior patterns emerge (i.e.,
calorie restriction, healthy food choices, and exercise). While there may be
some degree of “damage” to the brain, particularly in how hunger and satiety
hormones function, it can correct itself to a large degree over time. The key
is that the process does take time, and like any other behavior change, is
ultimately a practice. “We want to change behavior here,” says Hill. “Anyone
that tells you it’s going to happen in 12 weeks, that’s bogus. We’re trying to
rewire the brain. Neurobiology has told us so much about what’s going on in
weight gain and weight loss. It takes a long time to develop new habits,
rituals, routines. This takes months and years. But it will happen.”
* * *
So boiling it down even further: reduce calories, eat
better, exercise, and most of all, remember it is a practice that has to be
repeated over time – months or years. The fact that you’ll have to work harder
at maintenance than your never-overweight best friend is depressing, but it’s
worth coming to terms with. And, most important to remember, your brain (the
organ behind all this, after all) isplastic, and it will respond to the changes
you make – better than you think. And so will your body.
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