Protein has achieved superstar status in the media with high protein
diets dominating Hollywood headlines as the sure-fire way to lose
weight. You may have even tried one yourself. While most scientists
continue to refute the use of these more extreme diets, which are not
only high in protein but also high in fat and very low in
carbohydrates, they have been forced to question whether the
traditional low fat, high carbohydrate approach is in fact the best one
for everyone.
Support for high protein diets comes firstly from
the eating habits of our hunter-gatherer ancestors. Undoubtedly animal
produce and fish dominated their diets, with most of their carbohydrate
coming from fruits, vegetables and legumes rather than grain foods. The
latter only became a major part of our diets with the development of
agriculture some 50,000 years or so ago. They would, however, have
eaten considerable amounts of fruit and vegetables. Such a diet is not
low in carbohydrate and in fact their intake of vitamins, minerals,
fibre and antioxidants is estimated to have been considerably greater
than our intake today. This immediately refutes the healthfulness of
diets which restrict fruits and vegetables. Nutrition research over the
last few decades is compelling in support of the beneficial effects of
these foods in our diet.
More recent research has added
support to protein’s role in weight control. Protein has been shown to
be the most satiating of all three macronutrients. In other words, if
you include a protein-rich food in each meal it can help you to feel
full and satisfied for longer and in turn encourage you to stop eating.
One of the reasons for this is that protein slows down the stomach
emptying process, unlike a high-carbohydrate/low-fat meal which is
often digested quickly leaving you hungry again just as quickly.
Secondly protein takes the most energy to metabolise which means it is
less likely to be stored as fat. Protein-rich foods are also perceived
as being the enjoyable, tasty part of the meal – you usually order the
steak, fish or chicken rather than the potatoes or rice in a
restaurant. Finally by achieving a good balance of carbohydrate,
protein and fat at each meal you avoid overeating any one while
ensuring a good intake of all nutrients.
But this does not
mean you need to follow one of the popular high protein/low
carbohydrate approaches. Such diets are of concern for the following
reasons:
There is much scientific evidence showing the health
benefits of a diet rich in wholegrains. The detrimental data about
carbohydrates comes almost entirely from refined, processed and
therefore high GI carbohydrates.
High protein, low carbohydrate
diets are inevitably high in fat and usually much of it is saturated
fat. Such a fat intake may increase your risk of heart disease and
certain cancers in the long term.
These diets are monotonous and hard to maintain.
There is some concern over the additional load on the kidneys which may be damaging over time.
In
fact we can get the benefits of a little extra protein without
sacrificing good quality carbs or eating too much of the wrong type of
fat. The healthiest diet is one that contains good quality protein
alongside quality carbs and fats. Moderation might sound boring but it
really does seem to be the key.
Complementary Proteins for Vegetarians
Protein
is present in many foods. In fact almost all foods we have classified
as carbohydrate-rich also provide significant amounts of protein. This
has been taken into account when estimating the number of blocks of
each food group you need for your energy level. However, if you are
following a strictly vegetarian diet you need to give a little more
thought to ensuring you get the protein you need.
The building
blocks of proteins are amino acids. Of the hundreds that occur in
nature, about 20 are important in human nutrition Eight of these are
classified as strictly essential because our body cannot make them so
we must obtain them directly from our diet. Even a deficiency of one
essential amino acid would prevent your body from making all of the
proteins required for normal metabolism.
Meat, poultry, fish,
dairy products and eggs contain all of the essential amino acids and
are therefore sometimes termed high biological value (HBV) proteins.
Plant sources of proteins on the other hand tend to be low or lacking
in at least one of the essential amino acids and are sometimes referred
to as low biological value (LBV) proteins. This label is a little
unfair however, as it is not difficult to meet all of your amino acid
requirements from plant foods. It just means you have to eat
combinations of foods to obtain complementary proteins.
To
help ensure you are getting the right balance we can separate foods
into four protein groups as shown below. To maximise your variety of
amino acid intake aim to include at least two groups in the same meal
and across the course of day include them all. If you don’t eat dairy
foods and eggs it is even more important that you include all of the
other groups.
Because you are counting the Grains Group
as carbohydrate-rich and the Nuts Group as fat-rich, you may be finding
it hard to get all your protein blocks into one day even though you
will undoubtedly be getting enough protein to meet your body’s needs.
If this is the case, simply add one carbohydrate block for every two
protein blocks you deduct, aiming to keep as many protein blocks as you
can. Remember that you are counting the Legume Group as protein-rich
blocks and you should aim to include these everyday.
Examples of complementary protein meals for vegetarians:
Rice & beans
Toast & peanut butter
Tortilla & refried beans
Pita bread & hummus
Couscous & chickpea curry
Rice & tofu stir-fry
Oat porridge with mixed nuts & seeds
Breakfast cereal & milk
Pita bread with falafel
Sandwich with marinated tofu
Baked beans on toast