Grains are seeds of grasses that are cultivated only for the edible portion (seeds).
They are a rich source of vitamins, minerals, carbohydrates, fats, oils, and fibre.
Whole grains are grains in natural form whereas refined grains are those whose outer cover is removed and it is processed.
Whole grains are preferred as they are rich in nutrients while refined grains just contain carbohydrates.
Carbohydrates present in grains create controversy as to whether they cause weight gain or loss.
Definitely, certain foods are rich in carbohydrates and have a high glycemic index ( Glycemic index is the number allotted to the food indicating its effect on an individual’s blood glucose after consumption) which can cause weight gain.
But such foods can be replaced with food items with low GI.
For example, white bread has high GI and it can be replaced with whole grain bread.
Similarly, processed cereals can be replaced by whole grain unrefined cereals such as oats.
India is home to a large range of grains which is why we are famous for our variety of Indian bread.
Few of the grains that are commonly used are wheat, rice, jowar (great millet), bajra (pearl millet), ragi (finger millet), corn, and barley.
It is important to read food labels to confirm whether it is a whole grain product.
Whole wheat or hulled or hulless barley are examples of whole grain.
Grain and Weight Loss
Consumption of whole grain is associated with low BMI.
There are multiple mechanisms by which habitual whole grain consumption causes lower body weight, some of which are listed below:
- Whole grains are low in terms of energy density (low energy availability after digestion).
- They have low glycemic index which facilitates the breakdown of fats. Low glycemic index reduces fat storage and hunger.
- The non-digestible carbohydrates present in whole grains promote satiety.
- They have a positive influence on intestinal microflora whose functioning is linked to the development of obesity.
- The fibre content of grains increases the amount of chewing before ingestion of the food which promotes satiety.
Science on Grains and Obesity
Following research studies suggest the different types of grains whose consumption can help with weight loss and also indicate the mechanisms by which they act.
1. Wheat
Wheat is the most commonly consumed and produced grain worldwide. It is converted to flour which is used to prepare breads, cookies, pasta, cakes, fermented drinks etc.
Alkylresorcinols are a group of compounds found in wheat, rye, barley etc.
In an experimental study conducted on mice alkylresorcinols are found to suppress high fat and high sucrose diet-induced obesity.
Alkylresorcinols suppressed weight gain by 31% and improved liver function.
It also lowered elevated insulin, blood cholesterol, and leptin levels and positively balanced blood glucose levels.
These mechanisms suggest wheat alkylresorcinols have the potential of suppressing diet induced obesity.
A clinical trial investigated the effect of consumption of whole wheat and refined wheat on body weight.
Body weight reduced significantly in both groups however percent loss of body fat was more pronounced in whole wheat consumption group.
Refined wheat consumption elevated cholesterol levels while whole wheat did not have any such effect.
This indicates that whole wheat consumption can offer a cardioprotective role while helping with weight loss.
What does this mean? Apart from reducing obesity risk, wheat does reduce cardiovascular risks. Whole wheat is good for weight loss.
2. Oats
Oat is cultivated primarily in temperate regions such as Northwest Europe.
They are rolled or crushed into oatmeal or ground into oat flour. It is generally prepared as oat porridge, oatmeal cookies, oat bread etc.
Consumption of whole grain ready to eat cereal is proven to help with weight loss.
Oat cereals, when consumed for 4 weeks or more, were found to cause a significant reduction in cholesterol, waist circumference and blood lipid levels.
It also brought about significant weight loss however the weight reduction was comparable to that caused by low fiber foods.
A low-calorie diet containing oats when consumed for 6 weeks brought about improvement in cardiovascular risk factors.
A research study exploring this aspect of oats diet, reported that the oats diet helps in weight loss and decreases cholesterol levels as well as blood pressure.
The anti-obesity effect of oat has been proven by a clinical trial conducted in Taiwan. This effect is attributed to the fibre beta-glucan present in oats.
Consumption of oats reduced body weight, body fat, abdominal fat and waist to hip ratio.
Lipid profiles and liver function were also improved. It was proposed that consuming oats on a daily basis can aid in metabolic disorders.
Oat beta glucan as mentioned previously is a fibre that promotes weight loss by influencing hormones that regulate appetite and satisfaction after a meal.
Different doses of oat beta glucan along with energy-restricted diets were evaluated for their effect on weight loss in women.
Reductions in weight, waist circumference, cholesterol levels and appetite controlling hormones were observed however oats did not enhance the effect of energy-restricted diet on weight loss.
6 grams of concentrated oat beta-glucan when consumed daily for 6 weeks significantly reduces blood cholesterol and lipid levels.
It also improves colon health by beneficially modifying intestinal activity.
These factors once controlled can promote weight loss.
What does this mean? Do not ignore the advertisements which say that oat cereals help you lose weight. Yes, research proves that oats do help in losing weight.
3.Barley
Barley is one the first grains to be cultivated and is produced widely. It is rich in amino acids (basic units that makeup proteins).
Hulled or dehulled barley is considered as whole grain while pearl barley isn’t. It is used to prepare porridge, flour, soups, stews, and fermented drinks.
Barley exerts an appetite-controlling effect and reducing further energy intake. On the other hand, polished rice is said to cause weight gain.
An interesting study was conducted in Japan where white rice is a staple diet.
According to the study a meal of white rice in combination with beta glucan of barley reduced hunger and further food consumption and increased fullness before next meal.
It was suggested that this combination can be effective in preventing obesity.
Beta glucan found in barley improves insulin resistance.
It has been proven that consumption of barley can beta glucan can reduce weight gain, prevent fat accumulation in liver and improve insulin activity in mice fed with a high fat diet.
Fermented barley is proven to exert anti-obesity effect against diet induced obesity in animal model by controlling appetite influencing hormones that control appetite and reducing cholesterol levels.
Indigestible carbohydrates present in barley affect appetite and satiety.
Consumption of boiled barley kernels as an evening meal can reduce energy intake and suppress hunger over two subsequent meals.
This effect was due to modulation of appetite controlling hormones and reduction in cholesterol levels.
What does this mean? Barley prevents weight gain by regulating appetite and improving metabolic parameters like insulin and glucose.
4.Rice
Rice is a staple food for the majority of the population, especially in Asia.
Different types of rice are cultivated and the general notion is that white rice consumption leads to weight gain but not much evidence is available to support that idea.
Pigments present in other rice types are said to have nutritive value.
Low energy meal replacements of mixed rice (brown rice and black rice) are better in promoting weight loss than white rice.
In this study mixed rice meal showed a significant reduction in body weight, BMI and body fat in comparison to white rice.
Reduction in cholesterol levels was observed in both groups.
Improvement in antioxidant activities was higher in mixed rice group than white rice.
It was concluded that mixed rice meals should be used as a therapy for obese women.
Lees of brown rice is a by-product of fermentation process involved in manufacturing takju (Korean rice wine).
In a clinical trial involving type 2 diabetes patients, consumption of lees of brown rice resulted in significant reduction of waist circumference.
This is indicative of a possible role played by an extract of brown rice lees in metabolic diseases.
A comparative study between the effect of pre-germinated brown rice and white rice on symptoms associated with metabolic syndrome was conducted.
Pre-germinated brown rice is nothing but brown rice soaked in water which makes it easier and softer to eat.
Significant improvement in blood glucose, lipid levels, blood pressure, and other obesity-related parameters was observed after replacing white rice with pre-germinated brown rice in meals.
In a clinical trial focused on the effect of rice on inflammation in obesity, it was found that brown rice consumption brought about a great reduction in weight, waist and hip circumference, BMI and blood pressure compared to white rice consumption.
According to the study, brown rice can help decrease inflammation and cardiovascular risk factors in obese or overweight females.
What does this mean? Brown rice is a good option among the different types of grains available that aids with weight loss.
5.Buckwheat
Buckwheat is not related to wheat. It is referred to as a psuedocereal as it is not a grass but it is cultivated only for its seeds.
Buckwheat is generally prepared as porridge or flour and used to replace wheat and rice.
Buckwheat products can aid in influencing appetite.
A study conducted to examine nutritional properties of buckwheat starch reported that buckwheat products have low glycemic index.
It also contains starch resistant to digestion.
Further boiled buckwheat groats have the highest satiety score among other buckwheat products.
What does this mean? Buckwheat groats have a low glycemic index and they promote satiety. This can reduce subsequent food consumption and lead to weight loss.
6. Rye
Rye is a cereal grain that is related closely to wheat and barley. It is used to make flour, bread, fermented drinks etc. Rye is grown mainly in Europe.
Whole grain rye products promote a feeling of satiety upto 8 hours after a meal.
A study was conducted wherein subjects were given a breakfast of either whole grain rye porridge or refined wheat bread.
Whole grain rye porridge increased the feeling of satiety and lowered hunger ratings in comparison to refined wheat bread.
According to the study daily consumption of rye products can enhance satiety.
What does this mean? Rye food products can help with weight loss by controlling appetite.
7.Quinoa
Quinoa is a pseudocereal. It is a rich source of proteins and vitamins. It is grown in South America and is considered as a superior alternative to wheat.
Ecdysteroids are hormones that are not found in humans but their ingestion can support development of muscle mass.
Quinoa contains an ecdysteroid named 20 hydroxyecdysone.
Ignoring the scientific jargon, what we want to say is that this quinoa extract possesses anti-obesity property.
In an animal study, it was found that Quinoa extract reduced the size of fat cells, suppressed genes involved in fat storage.
It also reduced inflammation and insulin resistance.
It showed a protective effect on muscle proteins. According to the study, this extract of quinoa could be used as a nutritive supplement to treat obesity and related disorders.
What does this mean? Certain compounds present in quinoa exert an anti-obesity effect and this can be developed as a supplement. Till then you can start by incorporating quinoa food products in your diet.
8. Millet
Millet is consists of a variety of grains under one category. Few types of millets are grown in India and are known as jowar, ragi and naachanie.
It is cultivated in Asia and Africa. Most studies exploring the effect of millet on weight loss are conducted on animal models.
Finger millet bran can help with weight loss.
Finger millet bran supplementation prevented weight gain, improved lipid profile and anti-inflammatory status.
It also reduced oxidative stress (imbalance between prooxidant and antioxidant substances present in the body) and improved intestinal microflora.
According to the study these properties of millet can be used to treat high-fat diet-induced changes.
What does this mean? Millets can serve to be a good source of fibre and is proven to promote weight loss in animal models.
Whole Grains vs. Refined Grains
Whole grains are unprocessed grains that preferred over refined grains for their nutritive value.
Following studies demonstrate their role in weight loss.
To resolve the conflict between health benefits of whole grains and refined grains, researchers conducted an experimental study on obese individuals wherein the subjects were asked to consume a weight loss diet with either whole or refined grains.
Whole grain consumption led to lower body weight, low BMI and decreased the percentage of body fat and abdominal fat. A
lso, low glucose and cholesterol levels were observed in the group consuming whole grains.
A survey conducted in Norway reported the different diet habits of individuals with central obesity (abdominal fat).
Among the different dietary habits, central obesity was found to be linked with decreased consumption of whole grain bread and rice as well as increased intake of sugar-free drinks.
Findings suggested that poor dietary habits that promote central obesity could be of clinical importance.
Whole grains and refined grains influence body fat distribution.
Research proves that increased intake of whole grain is associated with low adipose tissue, in other words, low deposition of body fat, whereas a high intake of refined grains causes increased deposition of fat.
A clinical trial involving different interventions for weight loss found that a low-calorie diet rich in whole grain cereals along with exercise can reduce food intake more than exercise alone.
Diet rich in cereals along with exercise also reduced total fat and aided in weight maintenance.
The diet rich in whole grain cereal also provided fibre and micronutrients.
As per the study, a low-calorie diet rich in whole grain cereals can be effective in helping with weight loss and improving nutrient intake from diet.
What does this mean? Whole grains are superior to refined grains in terms of their effect on weight loss.
Caution
Coeliac disease is an autoimmune disorder affecting the small intestine.
It is characterized by digestive problems or vitamin deficiencies. It is caused by a reaction to the gluten protein found in cereals.
Individuals suffering from this disease can avoid conventional grains and opt for gluten-free cereals such as quinoa, millet, corn, rice etc.
Conclusion
Cereal grains are healthy carbohydrates and fibres.
For a healthy diet, one should consume at least one serving of grains each day. Consumption of cereal grains can enhance weight loss outcomes of low-calorie diet and exercise.
Always opt for whole grains. Get freshly ground wheat flour rather than readymade flour. Switch to partially polished rice. Choose brown rice over white rice.
Porridges and bread made from oats, millets, barley are healthy and a good change from routine.
Whole grains apart from helping with weight loss can add nutritive value to your diet in the form of vitamins and minerals.