The idea that humans can get all the nutrition they need in a pill
or a drink has been the stuff of science fiction for decades. Today,
life is imitating art, with many companies claiming to produce powders
which, when mixed with milk, water or juice, can provide all the
nutrients we need in a single efficient, calorie-controlled portion.
Such
drinks are often used as diet aids and at the popular end of the market
- where drinks like Slim Fast (and its various copycats) live - the
meal in a glass means that hopeful slimmers don’t have to spend hours
thinking about food, weighing food and balancing food groups in order
to lose weight.
For very obese individuals, this type of
calorie-controlled regime has been proven in medical studies (albeit,
more often than not, funded by Slim Fast) to be moderately successful -
at least in the short term.
In one Finnish study, for example,
100 participants were given either conventional foods or a regime where
meal replacements (Slim Fast shakes, bars and soups) were substituted
for two of the three main meals. In the first three months of the
trial, the meal replacement group lost, on average, 7.8 per cent of
their starting body weight, compared with 1.5 per cent in the food
group (Am J Clin Nutr, 1999; 69: 198-204).
Further follow-up
at four years showed that those who continued replacing one meal daily
with a meal replacement maintained their weight loss (Obes Res, 2000;
8: 399-402).
Another study, which substituted three meals a
day with calorie-controlled shakes (supplemented with fruits and
vegetables) over three months, resulted in similar weight loss compared
with a diet where women had a free choice of foods up to 1200 calories
per day. However, in the following nine months, only those who
continued to use the meal replacement for one meal per day maintained
their initial weight loss (J Am Diet Assoc, 2001; 101: 345-7).
Nevertheless,
meals in a glass have been criticised because they do not contribute to
improved eating habits (J Am Diet Assoc, 1991; 91: 1243-5; Int J Obes,
1999; 23: 553- 5; J Consult Clin Psych, 1999; 67: 177-85; Exp Clin End,
1998; 10: 22-6). Studies into their effectiveness may also be
misleading because, even though weight reduction is generally
beneficial, the simple fact of weight loss is not the best indicator of
health (Am J Epidemiol, 1996; 143: 228- 39; Nutr Rev, 1987; 45:
225-31).
Can’t get no satisfaction?
Intriguing evidence
also suggests that the body does not recognise calories from liquids as
effectively as it does calories from solid foods. In one study,
otherwise free-eating participants were asked to consume 450 calories’
worth of jelly beans every day for four weeks and then 450 calories’
worth of soda every day for another week, and to keep a record of what
they ate each day.
On the days the participants ate the
candies, they compensated by eating roughly 450 fewer calories’ worth
of other foods - so no more calories than usual were ingested. But on
the days they drank the sodas, the subjects didn’t compensate and, in
fact, ate roughly 450 calories more than usual. The researchers
concluded that liquid calories don’t trip our satiety mechanisms as
effectively as do solids (Int J Obes Relat Metab Disord, 2000; 24:
794-800).
Another study looked at the same problem from two
different angles. First, test subjects were given meals identical in
caloric content, weight, volume, composition and temperature, but
differed in that one was liquid and the other solid. In the second part
of the study, the test meals were composed of a liquid item and a solid
item. Both test meals were identical except that, in one meal, the
majority of calories came from liquid while, in the other, the majority
were from solid food. Results of the first part of the experiment
showed that the food intake in the 24 hours after the liquid meal was
higher than after the solid meal. Similarly, results of the second part
showed that when the majority of calories in the meal was consumed in
liquid form, the subsequent calorie intake was higher (Appetite, 1991;
16: 17-24).
One study found that men who consumed a
calorie-containing beverage with their meals wound up consuming more
calories than if they drank a calorie-free beverage (Physiol Behav,
1990; 58: 19-26).
Our ratings
Judging any type of food is
often a subjective exercise. While we allocated points for the taste
and texture of the shakes, we also looked for objective markers of
nutritional quality. Each product was assessed according to its
carbohydrate and protein content. We took points off for excessive
sugar content, and also for megadoses of protein, which can be just as
unhealthy (see box on page 3 ). We looked at vitamin and mineral
content as well as calories per serving and fibre content. We also
looked for extra and dubious ingredients such as artificial sweeteners.
Finally, we looked at price, including a pint of milk (40 p) where
appropriate. As each of these products has a different serving size,
ranging from 220-330 mL, to make a fair comparison, we broke the price
down into both per serving and per 100 mL of each product.
For
an overall comparison, we used guidelines from the London-based
Institute for Optimum Nutrition, which suggest that a well-balanced
diet should be made up of approximately 15 per cent protein, 70 per
cent carbohydrate and 15 per cent fat, with a daily fibre intake of
around 35-45 g.
On this basis, none of the products tested came
even close to being well-balanced, and some were little different from
standard chocolate milk drinks (see box above for comparisons).
Although users are supposed to include at least one ‘well-balanced’
meal daily on a meal-replacement regime, with most of these products,
this would still not necessarily guarantee an overall balanced diet. In
those drinks that have a greater carbohydrate-to-protein ratio, the
carbohydrates are made up mainly of sugars, which effectively negate
any potential benefit. We would also have liked to have seen much more
advice with each of these products about drinking water - especially
necessary with the higher-protein shakes and for drinks containing
fibre.
AdvantEdge
Distributor: EAS
Price: £1.49 for 330 mL
Rating: **
This
premixed meal replacement is one of many made by EAS (Experimental and
Applied Sciences), one of the more popular manufacturers in the US.
Previously available only through branches of the American healthfood
chain GNC, these products are finding their way into independent
healthfood shops, and can now even be found in larger branches of some
supermarket chains such as Sainsbury’s.
EAS makes a number of
products for serious bodybuilders, including the popular Myoplex - a
high-protein, low-carbohydrate nutrition shake.
AdvantEdge,
however, is aimed squarely at the Slim Fast market, and there is little
between the two products in terms of their sugar content, caloric
values, and levels of vitamins and minerals they offer. The vanilla and
chocolate flavours are acceptable and have a reasonably creamy texture,
but it’s best served cold. However, AdvantEdge contains chromium, which
can enhance insulin sensitivity, so we were surprised to find no
warning to diabetics, who should avoid products with this mineral.
At
£1.49 per serving, or 45 p per 100 mL, you are probably paying more for
the convenience factor of a premixed drink and the association with a
known sport-nutrition company.
Max-Meal
Distributor: Maxi-Muscle
Price: £34.99 for 20 85-g sachets (20 servings)
Rating: **
A
serious meal replacement for gym addicts, this is relatively high in
calories (320 per serving) compared with its competitors and contains a
massive 52.7 g of protein per serving when mixed as directed with
water. Replacing two meals a day would give you a decent amount of
calories, but also almost five times the adult recommended daily intake
of protein. Unusually, this product derives its protein from whey,
which makes for a creamier-tasting mixture. But its high protein
content means that it is only suitable for those who are involved in
regular, strenuous body-building, whose protein requirements are much
higher than average. It also contains the artificial sweetener
acesulfame K and sugar-free sweetener xylitol, both of which can cause
stomach upsets.
Max-Meal costs £1.75 per serving, or approximately 50 p per 100 mL.
Slim Fast
Distributor: Sun Nutritional
Price: £6.49 for a 420-g can (12 servings)
Rating: **
The
best known of all these meal replacements is a soya-based drink. It
contains no artificial sweeteners, but plenty of sugar, which may be
part of its appeal. To be palatable, Slim Fast needs to be mixed in a
blender with very cold milk and preferably ice - which seems to help
thicken it. Mixed in this way, it’s like drinking a milkshake for
lunch, and this guilty pleasure may be one reason why Slim Fast is a
market leader.
Slim Fast comes in chocolate, vanilla, strawberry
and banana flavours, and can be put in a blender with fruit to boost
both the nutritional quality and taste. A single serving of Slim Fast
has more fibre than all the other drinks combined. Some of this fibre
content is from inulin (an important water-soluble fibre obtained from
Jerusalem artichokes).
The cost of a Slim Fast drink is around 70 p per serving, or 32 p per 100 mL.
Spiru-Tein
Distributor: Nature’s Plus
Price: £16.95 for 476 g (14 servings)
Rating: **
Manufacturer
Nature’s Plus claims on the label that one of the ingredients is love.
This soya-based shake also contains spirulina, a type of algae, as well
as added oat bran and apple pectin. Despite this, it is very low in
fibre, so long-term use may mean that dieters won’t get the fibre they
need. Soya protein can also be difficult to digest, which may be why
this product includes papaya and the digestive enzyme bromelain.
However, it also contains chromium, so diabetics should beware.
Spiru-Tein
comes in vanilla and chocolate flavours, and can be mixed with water,
milk or juice (vanilla is probably more appropriate for the latter).
For best results, the liquid should be very cold and, although it is
supposed to mix instantly, we found that using a blender gave better
results.
The cost when mixed with milk worked out at £1.37 per serving, or 62 p per 100 mL.
Diet Fuel
Distributor: Twinlab
Price: £22.99 for 708 g (19 servings)
Rating: *
Diet
Fuel contains no fat, no fibre and no sugar. Mixed as recommended with
8 oz of water, this drink tasted much like you’d expect 120 calories to
taste - thin and uninteresting. In a blender with ice, the chocolate
had more appeal; the vanilla mixed with fruit stood up better too. Yet
again, though, it contains chromium picolinate, which diabetics should
avoid except when taken under medical supervision. Also, it uses
aspartame, which can cause uncomfortable symptoms such as heart
palpitations and headaches.
Following a regime that replaces two
or three meals daily with this product would mean you are taking in
less than 1000 calories daily - a dangerously low level.
Ironically,
given how little is in it, this was the among the more expensive brands
we surveyed. Dining on Diet Fuel will cost you £1.21 per serving or 55
p per 100 mL.
Source of Life
Distributor: Nature’s Plus
Price: £18.35 for 507 g (13 servings)
Rating: *
An
‘energy shake’ based on (non-GMO) soya protein, the ingredients in this
mix differ significantly from the others in this review. Source of Life
is more of a supplement than a meal in a glass, and uses concentrated
whole foods to provide a reasonable range of vitamins and minerals. It
includes fruit and vegetable concentrates, bioflavonoids, digestive
enzymes, good fats, carotenoids, bee pollen, ginseng, Astragalus,
ligstrum berry, schisandra, barley, Echinacea, Irish moss, thyme and
spirulina.
This may be most useful for convalescents or
children who won’t eat. The green colour may put some people off and,
even with vanilla flavouring, a slight aftertaste of spirulina lingers.
Mixed with milk, it costs £1.73 per serving, or 78 p per 100 mL - the
most expensive drink we tested.
Fast food is here to stay and
the market for liquid meal replacements is growing each year.
Nevertheless, if this investigation is anything to go by, we are still
a long way from the science fiction ideal of a truly well-balanced and
nutritious meal in a glass.
Product Calories Protein Carbohydrate (sugars) Fats (saturates) Fibre
AdvantEdge 200 15.0 27.0 (23) 4.6 (0) 1.1
Diet Fuel 120 20.0 9.0 (0) 0 (0) 0
Max-Meal 320 52.7 10.4 (2.6) 8.0 (5.7) 1.87
Slim Fast* 213 13.8 32.0 (27.6) 3.5 (0.8) 6.0
Source of Life 196 21.0 28.0 (21) 0 (0) 1.0
Spiru-Tein 176 22.0 22.0 (18) 0 (0) 1.0
And just for the record . . .
Ovaltine** 185 8.4 29.6 (21.7) 3.7 (2.3) 0.6
All figures except for calories denote grams per serving; *Chocolate Royale flavour;
**Original formulation, mixed with 200 mg skimmed milk (28 pence per serving)
It pays to look at the label with a critical eye when choosing meal replacements. Important information includes:
* Carbohydrates
Many
meal replacements claim to give you energy. Think carefully about this
claim as energy is just another word for calories. The energy-boosting
carbohydrates in most meal replacements are often just sugar. In fact,
in some of them, sugar is the main ingredient, though often dressed up
in a selection of other names such as fructose, glucose, dextrose,
maltose, corn syrup, rice syrup and barley syrup. Sugar contains no
nutrients and the energy you get from it is short-lasting and often
followed by more pronounced feelings of fatigue and a loss of energy.
* Sweeteners
Even
less satisfactorily, those that don’t contain sugar use artificial
sweeteners, such as the excitotoxin aspartame and acesulfame K. These
neurotoxic compounds have been associated with a variety of problems,
ranging from headache, skin rash and digestive disorders to brain
tumours (J Neuropathol Exp Neurol, 1996; 55: 1115-23). Sugar-free
sweeteners such as xylitol, associated with stomach upsets, are also
common ingredients.
* Protein
Protein is hugely hyped as a
power nutrient. In reality, the body needs protein, carbohydrates and
fat to fuel it properly. Professional body-builders need in excess of
300 g of protein daily. The rest of us only need around 35 g of protein
daily. In fact, most of us eat in excess of this, with the average diet
containing two to three times what we need. In general, high protein
intake over the long term is associated with deteriorating kidney
function and even osteoporosis.
Consider also the sources of
protein in meal replacements. These days, it is usually soya (in fact,
all but one of the sampled drinks was soya-based). Drinking
high-protein shakes based on soya several times a day over the long
term can potentially result in a body that is profoundly biochemically
disrupted. Problems with excessive consumption of non-fermented soya
like this are numerous. The high levels of phytic acid in soya reduce
the body’s absorption of calcium, magnesium, manganese, molybdenum,
copper, iron and zinc while increasing the requirement for vitamins E,
K, D and B12.
Soya phytoestrogens disrupt endocrine function
and are potent antithyroid agents that can lead to hypothyroidism. The
processing of soya protein at high temperatures can reduce its
nutritive value, and results in toxic lysinoalanine and highly
carcinogenic nitrosamines. Soya foods also contain high levels of
aluminium, which is toxic to the nervous system and kidneys (see PROOF!
vol 4 no 4, pages 2-6). Consumers should remember that soya is often
the base for such products not because it is particularly good protein,
but because it is cheap.
The other usual source of protein is
whey - a dairy-based source of amino acids. While athletes sometimes
take extra whey protein supplements, there has not been any evidence
that doing so increases athletic performance. People who are allergic
to dairy products could react to whey as could those who are
lactose-intolerant.
* Other ingredients
These include
vitamins and minerals, but also phytochemicals that you have to
scrutinise the label carefully to find. Most often, these are digestive
aids such as papain and bromelain. But more sophisticated mixes can
contain herbal extracts such as ginseng, hydroxycitric acid (a.k.a.
CitriMax or Garcinia cambogia), Echinacea, borage oil, garlic,
Astragalus, Gingko biloba and even St John’s wort. In the world of
serious body-building, controversy reigns regarding the addition of
herbal anabolic steroid precursors (even if they are not always listed
on the label). In the average meal replacement, it is unlikely that
these will be present in enough quantity to boost health, though they
will help to boost the price of the product.