Can eating fruits and vegetables help people to manage their weight?

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Transcript Can eating fruits and vegetables help people to manage their weight?

Can eating fruits and
vegetables help people to
manage their weight?
There are many proposed strategies for losing
or maintaining weight.
This presentation looks at only one strategy:
substituting low-energy-dense fruits and
vegetables for foods with high energy density in
order to lower the number of calories consumed.
References to all studies are in “Can fruits and vegetables help people to
manage their weight?” in the CDC Web site: and in the notes in this electronic
PowerPoint presentation.
What Is Energy Density?
It is the relationship of calories to weight
of food (i.e., calories per gram).
All foods are in one of three categories:
 High-energy-dense foods: 4-9 calories per gram
(e.g., cookies, crackers, butter, bacon)
 Medium-energy-dense foods: 1.5-4 calories per gram
(e.g., bagels, dried fruits, hummus, part-skim mozzarella)
 Low-energy-dense foods: 0.0-1.5 calories per gram
(e.g., most fresh fruits and vegetables, fat-free yogurt)
Dietary Guidelines for Americans (2005)
“…calorie-lowering strategies include eating
foods that are low in calories for a given
measure of food (e.g., many kinds of
vegetables and fruits and some soups).”
“…make substitutions to avoid excessive
calorie intake.”
Volume, Density, and Calories in
Weight Management
 Feeling full is one reason people stop eating.
 Volume affects the feeling of being full.
 Low-energy-dense foods have fewer calories than the
same volume of high-energy-dense foods. People who eat
low-energy-dense foods can feel full while eating fewer
 Water and fiber increase volume and reduce energy
 Fruits and vegetables have high water and fiber content
and are relatively low in calories and energy density.
Conclusion: Fruits and vegetables are good substitutes
for high-energy-dense foods in a weight management
So how do people lose weight?
 To lose weight people must consume fewer
calories than they expend.
Eating fewer calories is difficult, but
feeling full is one reason that people stop
 The amount or volume of food a person eats
prompts a feeling of being full.
One study* provides evidence that feeling full is
more likely to make a person stop eating than
the total calories consumed.
 For 5 days, 20 participants ate as much as they
wanted from food offered to them over 5 days.
 The diet alternated from low-energy-dense to
high-energy-dense foods.
The participants felt full on the low-energydensity diet after eating just over half the calories
(1570 kcal) they consumed before feeling full on
the high-energy-density diet (3000 kcal).
* Duncan KH, Bacon JA, Weinsier RL. The effects of high and low energy density diets on satiety, energy intake, and eating time of
obese and nonobese subjects. Am J Clin Nutr 1983;37:763-7.
Eating low-energy-dense foods =
Fewer calories consumed than when eating
high-energy-dense foods, but feeling equally full
 For 2 days, researchers provided meals and snacks for 2
days to women who were assigned to a low-, medium-, or
high-calorie menu.
 The women in each group ate until they were full.
 All groups of women ate a similar amount, or volume, of
 The study suggests that the volume of food, not calories,
makes people feel full.
Bell EA, Castellanos VH, Pelkman CL, Thorwart ML, Rolls BJ. Energy density of foods affects energy intake in normal-weight
women. Am J Clin Nutr 1998;67:412-420.
Volume affects energy density
and the feeling of being full.*
 Yogurt milkshakes were given 30 minutes before lunch
on 3 different days.
 The shakes came in three sizes: 300 ml, 450 ml, and 600
ml, BUT had equal calories.
 (Higher volumes were achieved by incorporating air.)
 Participants consumed 12% fewer calories at lunch after
drinking the 600 ml milkshake.
 Participants reported greater feelings of fullness after
drinking the 450 ml milkshake or the 600 ml milkshake
than after the 300 ml drink.
*Rolls BJ, Bell EA, Waugh BA. Increasing the volume of a food by incorporating air affects satiety in men. Am J Clin Nutr
Water, Energy Density, and the Feeling of Being Full
On 3 different days during a 4-week study*
 24 women ate the same foods over 3 days, but prepared differently
each day
 Day 1: chicken-rice casserole (1 1/3 cups).
 Day 2: chicken-rice casserole (1 1/3 cups) with a glass (8 oz.) water.
 Day 3: chicken-rice soup (2½ cups) made by adding 8 oz. water into
the casserole ingredients used the previous day.
Eating the soup (compared to the foods on other days)
- Significantly increased the feeling of being full.
- Reduced the participants’ hunger.
- Significantly reduced the number of calories the women consumed
during lunch.
*Rolls BJ, Bell EA, Thorwart ML. Water incorporated into a food but not served with a food decreases energy intake in lean women.
Am J Clin Nutr 1999;70:448-55.
A literature review* found similar findings:
 Short-term studies: Low-energy-dense foods promoted
feeling full, reduced hunger, and provided fewer calories.
 Long-term studies: Low-energy-dense foods promoted
moderate weight loss.
 Studies lasting longer than 6 months: Weight loss was
three times greater for people who ate foods of low
energy density than for those who simply ate low-fat
*Yao M, Roberts SB. Dietary energy density and weight regulation. Nutr Rev 2001;59:247-58.
Fruits and Vegetables = Low Energy Density
 Fat increases the energy density of foods.
 Water and fiber in foods increase volume and
reduce energy density.
 In their natural state, fruits and vegetables have
high water and fiber content and are low in fat
and energy density.
The USDA’s Web site on food composition
( lists water and fiber
content, as well as other food components, including
calories, for hundreds of vegetables and fruits.
Studies* with fruit and fruit juices show:
 Whole fruit is more satiating.
 Whole fruit contains fiber, and juice is fiber-free.
*Haber GB, Heaton KW, Murphy D, Burroughs LF. Depletion and disruption of dietary fibre. Effects on
satiety, plasma-glucose, and serum insulin. Lancet 1977;2:679-88.
*Bolton RP, Heaton KW, Burroughs LF. The role of dietary fiber in satiety, glucose, and insulin: studies with
fruit and fruit juice. Am J Clin Nutr 1981;34:211-17.
Vegetables, Fiber, Water, and Feeling Full
In a series of studies* by Gustafsson and colleagues:
 Researchers found that adding vegetables (carrots and
spinach) to meals but keeping the same number of
calories enhanced the feeling of being full if at least 200 g
of vegetables were added.
 Ratings of fullness were correlated positively with the
fiber content, water content, and total weight of the meal.
*Gustafsson K, Asp N-G, Hagander B, Nyman M. Effects of different vegetables in mixed meals on glucose homeostasis and satiety.
Eur J Clin Nutr 1993;47:192-200.
Gustafsson K, Asp N-G, Hagander B, Nyman M. Dose-response effects of boiled carrots and effects of carrots in lactic acid in mixed
meals on glycaemic response and satiety. Eur J Clin Nutr 1994;48:386-96.
Gustafsson K, Asp N-G, Hagander B, Nyman M. Satiety effects of spinach in mixed meals: comparison with other vegetable Int J
Food Sci Nutr 1995:46:327-34.
Gustafsson K, Asp N-G, Hagander B, et al. Influence of processing and cooking of carrots in mixed meals on satiety, glucose and
hormonal response. In J Food Sci Nutr 1995;46:3-12.
Dietary Fiber and Weight Management
 In a review* of 22 studies, 20 studies found that highfiber diets resulted in weight loss.
 Even in studies that did not restrict food intake,
participants on high-fiber diets lost significantly more
weight than those on the low-fiber diets.
 An increase of 14 g of fiber per day was associated with
an average weight loss of more than 4 lb. within nearly 4
months, based on pooled data from 12 studies.
*Howarth NC, Saltzman E, Roberts SB. Dietary fiber and weight regulation. Energy density of foods affects energy intake across
multiple levels of fat content in lean and obese women. Am J Clin Nutr 2001;73:1010-18.
Review* of Dietary Intervention Studies
Many studies have found that significant weight
loss can occur when advice to increase the intake
of fruits and vegetables is coupled with advice to
reduce energy intake.
*Rolls BJ, Ello-Martin JA, Tohill BC. What can intervention studies tell us about the relationship between fruit and vegetable
consumption and weight management? Nutr Reviews 2004;62:1-17.
Intervention 1: MRFIT*
Multiple Risk Factor Intervention Trial
 Participants were advised to reduce their fat intake and
increase consumption of fruits and vegetables and whole
grains to help them lose weight and improve their blood
lipids and blood pressure.
 Increases in fruit and vegetable intake were related to
maintenance of weight loss.
 Participants who lost more weight ate more fruits and
vegetables than the others.
*Dolecek TA, Stamler J, Caggiula AW, et al. Methods of dietary and nutritional assessment and intervention and other methods in
the Multiple Risk Factor Intervention Trial. Am J Clin Nutr 1997;65(suppl 1):196S-201S.
Intervention 2: Reduced Calories, Low Fat, and High
Complex Carbohydrates*
 Allowed unlimited fruits and vegetables for 6 months.
 147 (69%) of the 213 adult participants lost weight
(average: 14 lb).
 During 25 months of follow-up—
- 53% of the participants continued to lose or maintain
their weight.
- The mean net weight loss from pretreatment to the end
of follow-up was more than 17 lb.
*Fitzwater SL, Weinsier RL, Wooldridge NH, et al. Evaluation of long-term weight changes after a multidisciplinary weight control
program. J Am Diet Assoc 1991;91:421-4.
Intervention 3: Families with Obese Parents and a
Nonobese Child*
 Parent-focused behavioral intervention.
 Two groups: Both had a comprehensive behavioral program.
- One group increased fruit and vegetable consumption.
- Second group decreased their intake of high-fat and high-sugar
 Materials for the children targeted the same dietary changes as for
their parents, but with no calorie restrictions.
After 1 year:
- Parents in the increased fruit and vegetable group experienced
greater decreases in weight than parents in the decreased fat and
sugar group.
- Parents and children in the increased fruit and vegetable group also
decreased consumption of high-fat and high-sugar foods.
*Epstein LH, Gordy CC, Raynor HA, Beddome M, Kilanowski CK, Paluch R. Increasing fruit and vegetable intake and decreasing fat
and sugar intake in families at risk for childhood obesity. Obesity Res 2001;9(3):171-8.
Intervention 4: Increased Fruits and Vegetables with
Decreased Fat Intake*
 Participants consumed a daily diet that included specific
amounts of fruits, vegetables, juice and fiber, and
provided 15%-20% of energy from fat.
After 1 year:
 Energy-adjusted intake of vegetables and dietary fiber,
but not fruit, was associated with a decrease in body mass
index (BMI).
 A decrease in percent energy from fat was not associated
with a drop in BMI.
*Rock CL, Thomson C, Caan BJ, et al. Reduction in fat intake is not associated with weight loss in most women after breast cancer
diagnosis: evidence from a randomized controlled trial. Cancer 2001;91:25-34.
Intervention 5: Polyp Prevention Trial*
Participants who increased their intake of fruits and
vegetables and decreased their fat intake lost a
significant amount of weight in 1 year.
*Lanza E. Schatzkin A, Daston C, et al. Implementation of a 4-y, high-fiber, high-fruit-and-vegetable, low-fat dietary intervention:
results of dietary changes in the Polyp Prevention Trial. Am J Clin Nutr 2001;74:387-401.
Intervention 6: Cardiac Trials—
Lower Fat and Increased Fruits and Vegetables
In a series of trials, cardiac patients who changed
their diets by lowering their fat intake and
increasing their consumption of fruits and
vegetables lost a significant amount of weight.
*Singh RB, Rastogi S, Verma R, et al. Randomised controlled trial of cardioprotective diet in patients with
recent acute myocardial infarction: results of a one year follow up. Br Med J 1992;304:1015-9.
Singh RB, Rastogi S, Niaz MA, et al. Effect of fat-modified and fruit- and vegetable-enriched diets on blood
lipids in the Indian Diet Heart Study. Am J Cardiol 1992;70:869-74.
Singh RB, Dubnov G, Niaz MA, et al. Effect of an Indo-Mediterranean diet on progression of coronary artery
disease in high risk patients (Indo-Mediterranean Diet Heart Study): a randomized single-blind trial.
Lancet 2002;360:1455-61.
Research Review
 Very few studies examined a direct relationship between
eating fruits and vegetables and losing weight.
 Some studies had few participants.
 Many studies focused on fruits and vegetables in the
context of treating high blood pressure or cardiac
disease—but also reported on weight loss.
 Some studies examined the short-term impact of eating
fruits and vegetables on energy intake.
 Feeling full cues people to stop eating.
 People feel full based on the volume of food consumed,
not necessarily on the number of calories in the food.
 Eating low-energy-dense foods can help people feel full
with fewer calories.
 Replacing foods of high energy density (high calories per
weight of food) with foods of low energy density, such as
fruits and vegetables, can be an important part of a weight
management strategy.
Tips for Eating Fruits and Vegetables in a
Weight Management Program
 Fruits and vegetables should be substituted for
foods high in energy density.
Tips for Eating Fruits and Vegetables in a
Weight Management Program
 To lower the energy density of foods, such as
soups, sandwiches, and casseroles, substitute
fruits and vegetables for some of the ingredients
that have higher energy density, such as high-fat
meat, cheese, and pasta.
Tips for Eating Fruits and Vegetables in a
Weight Management Program:
 Breading and frying vegetables or adding highfat dressings and sauces greatly increase the
calorie and fat content of the dish.
 Some desserts that include fruit may also have
high calorie, fat, and sugar content.
Tips for Eating Fruits and Vegetables in a
Weight Management Program
 Eat whole fruit instead of drinking juice.
 Frozen and canned fruits and vegetables
are good options when fresh produce is not
available. Choose items without added
sugar, syrup, cream sauces, or salt.
Tips for Eating Fruits and Vegetables in a
Weight Management Program
 Vegetables tend to be lower in calories
than fruit. Substituting more vegetables
than fruit for foods of higher energy
density can be helpful in a weight
management plan.
Types of Fruits
 Fruit is the sweet, fleshy, edible portion of a plant. It generally
contains seeds. Fruits are usually eaten raw, although some
varieties can be cooked. They come in a wide variety of colours,
shapes and flavours. Common types of fruits that are readily
available include:
 Apples and pears
 Citrus – oranges, grapefruits, mandarins and limes
 Stone fruit – nectarines, apricots, peaches and plums
 Tropical and exotic – bananas and mangoes
 Berries – strawberries, raspberries, blueberries, kiwifruit and
passion fruit
 Melons – watermelons, rock melons and honey dew melons
 Tomatoes and avocados.
Types of Vegetables
 Vegetables are often cooked, although some kinds (salad
vegetables) are eaten raw. Vegetables are available in
many varieties and can be classified into biological
groups or ‘families’, including:
 Leafy green – lettuce, spinach and silverbeet
 Cruciferous – cabbage, cauliflower, brussel sprouts and
 Marrow – pumpkin, cucumber and zucchini
 Root – potato, sweet potato and yam
 Edible plant stem – celery and asparagus
 Allium – onion, garlic and shallot.
 Legumes or pulses contain nutrients that are especially
valuable. Legumes need to be cooked before they are eaten –
this improves their nutritional quality, aids digestion and
eliminates any harmful toxins. Legumes come in many forms
 Soy products – tofu (bean curd) and soybeans
 Legume flours – chickpea flour (besan), lentil flour and soy
 Dried beans and peas – haricot beans, red kidney beans,
chickpeas and lentils
 Fresh beans and peas – green peas, green beans, butter beans,
broad beans and snow peas.
Colour is the key to healthy food
 Maximum health and protection against
disease comes from eating a wide variety
of fruits and vegetables. The National
Health and Medical Research Council
(NHMRC) guidelines recommend that
adults eat at least five kinds of vegetable
and two kinds of fruit every day.
 Foods of similar colours generally contain similar protective
compounds so try to eat a rainbow of colourful fruits and
vegetables every day to get the full range of health benefits.
For example:
 Red foods – like tomatoes and watermelon contain lycopene,
which is thought to be important for fighting prostate cancer
and heart disease.
 Green vegetables – like spinach and kale contain lutein and
zeaxanthin, which may help protect against age-related eye
 Blue and purple foods – like blueberries and eggplant contain
anthocyanins, which may help protect the body from cancer.
 White foods – like cauliflower contain sulforaphane, which
may also help protect against some cancers.
Things to Remember
 Fruits and vegetables contain important vitamins,
minerals and ‘plant chemicals’.
 There are many varieties of fruit and vegetables
 Eat 5 kinds of vegetable and two kinds of fruit
every day for good health.
 A diet high in fruit and vegetables can help
protect against cancer, diabetes and heart disease.
Right Way to Cook Vegetables
 You go out of your way to buy the freshest, peakseason vegetables, not only because they taste good but
also because they’re packed with vitamins, minerals,
and antioxidants. But did you know that how you cook
them makes a huge difference in how well they retain
those nutrients? Some cooking methods preserve
nutrients and even help them enter your bloodstream,
while others can destroy them. So once you get those
vegetables home from the market, look to the strategies
here to get the most nutritional bang for your buck.
Limit the Water
 When you cook vegetables in water, you lose
nutrients. You know that green hue the water
takes on after you’ve boiled or blanched your
broccoli? That’s a sign that vitamins like C and
B have leached into the water, only to be
poured down the drain. To retain these
vitamins, cook vegetables in as little water as
possible for a minimal amount of time (unless
you’re planning to consume the water, as in a
 Steaming and microwaving, both of which
use little water, will give you the same
results as boiling or blanching but with
much less nutrient loss. So instead of
boiling potatoes before mashing them,
steam them. Instead of blanching broccoli,
green beans, or asparagus, steam or
microwave them until crisp-tender.
 Similarly, if you want your vegetables
cooled, don’t plunge them into an ice bath;
like hot water, cold water can also leach
nutrients. Instead, cook vegetables for a
minute less and then spread them in a
single layer on a baking sheet so they’ll
cool quickly at room temperature.
Use a Little Fat
 Eating plain steamed vegetables may sound
like the best way to go nutritionally, but
you’re actually better off eating vegetables
with some fat. Many nutrients, like beta
carotene, vitamin D, and vitamin K are fat
soluble, so they can only pass from our
intestine into our blood stream with some fat
to carry them across.
 It’s like a nutritional buddy system. So toss
those steamed veggies with a flavorful
vinaigrette, or sauté or stir-fry them—all of
these methods use some fat (which helps
maximize absorption) but little if any water
(to minimize nutrient loss). They’ll also make
your vegetables tastier than plain steamed
ones, so you’ll be inspired to eat more.
Add Citrus
 Vegetables like spinach, broccoli, and kale contain lots
of iron, but it’s in a form that’s difficult for our bodies
to use, so most of it passes through undigested.
Vitamin C, which citrus fruits provide in spades, reacts
with iron chemically, changing it into a form that’s
more easily absorbed by our bodies. In other words, it
makes the iron user-friendly. So go ahead and add a
splash of lemon, lime, orange, or grapefruit juice to
that stir-fry or sauté.
 The three strategies here are all used in the recipe
opposite; it’s a perfect example of how to
maximize nutrition in a delicious way. The green
beans are briefly steamed instead of boiled. Then
they’re sautéed with yellow peppers and shallots in
a touch of healthful olive oil until just tender. Fresh
spinach is tossed in at the end, and the dish is
finished with splash of orange juice. I can’t think
of a better way to get the most out of your
Good to Know!!!
Cooking affects how vegetables retain nutrients, but
how you prep them matters, too. Here are some tips:
• Wash before cutting Cutting a vegetable breaks its
cell walls, allowing nutrients to escape into any water
on contact. By washing uncut vegetables, nutrients stay
safely tucked inside their cell walls and won’t be
leached into the water.
• Keep the peel on Many key nutrients are found in or
just under the vegetable peel, so leave the peel on
whenever possible.
 • Cook soon after cutting Nutrients can be
destroyed when exposed to light and air. Cook
and eat vegetables soon after cutting to keep
vitamins and minerals secure in their cells as long
as possible.
• Cut larger, uniform pieces Larger pieces mean
fewer cell walls severed and fewer nutrients lost
to heat, light, or cooking water. Cutting uniform
pieces ensures that everything is done at the same
time, eliminating overcooked pieces and loss of