The principles of nutrition are rather confounding. Various studies come up with diverging and conflicting results and everyone has a different set of argument which supports or opposes the study.
Same is the case with fats. One moment you enjoy drizzling olive oil on every next meal, the other moment you are advised to go fat free.
Fats make you fat would be true only if sugars made you sweet or tomatoes made you tangy. After all you are what you eat, right!? Nevertheless this article should help you make a sound decision as to whether fats really make you fat or no?
What is the role of fats in the body?
Fats provide the maximum energy among the dietary nutrients: 9kcal per gram. Its primary functions in our body are:
- Source of energy: Carbohydrates are the primary source of fuel for our body. But in the absence of carbohydrates, our body utilises fat as a source of energy. Fats have high calorific value. Furthermore, only 2% of energy from fats is required to break it down making it the most energy efficient fuel.
- Insulator: Fats are stored in the fat tissue. It is present under the skin, inside and between muscles, in cell membranes and around organs for protection. It helps sustain an optimal body temperature.
- Biochemical functions: They act as messengers that signal proteins to do their job and participate in chemical reactions like growth, immune function etc.
- Store nutrients: Certain nutrients are made available to our body only by presence of fats. Fat soluble vitamins A,D, E, K cannot function without adequate fat. Vitamin A is good for eyes, Vitamin D is essential for bones, Vitamin E serves as an antioxidant and Vitamin K is vital for blood clotting.
So for those of you who think you are getting healthier by not consuming fats, that not the case in reality.
Note: Fats are an essential dietary component that play important roles in our body such as insulation, nutrient storage, energy production etc.
The Good Fats and The Bad Fats: What to Eat and what not to?
Not all fats are equal. Fats are divided into a number of types based on their chemical structure. And based on their effect on health primarily heart health they are classified as good and bad fats. Lets get some details about them.
The good fats are mainly the unsaturated fats. Fats contain carbon and hydrogen. Those that are not saturated with hydrogen are known as unsaturated fats.
- Monounsaturated fats (MUFA): They are found in varying levels in oils like olive, sunflower, sesame, flax, peanut, safflower, etc.
- Polyunsaturated fats (PUFA): They are found in corn, soybeans, grains and peanuts.
Sunflower,sesame, pumpkin seeds
Saturated fats and trans fat are considered the bad guys because apparently they raise the cholesterol levels and increase the risk of developing heart diseases.
Saturated fats: They are saturated with hydrogen and are solid at room temperature. Meat and whole fat dairy product are prime sources. These are a little controversial. Some studies reflect that can cause obesity, inflammation and high cholesterol levels while some say that they have no or little effect on cholesterol and obesity .
So it is not like these are a total no-no. Most of the studies proposing the use of saturated fats recommend low saturated fat diets. Reducing intake of saturated fat to 10% of your daily calories or less and obtaining them from healthy sources like palm oil and coconut oil can indeed help in weight loss.
Trans fats: These are the real villains. They can occur naturally or are prepared by changes in chemical structure of unsaturated fats. Basically unsaturated fats undergo a process of hydrogenation where they are converted to harmful trans fat. These are a simple no-no. They are found in every next processed snack.
|High fat cuts of meat
Chicken with skin
Whole fat dairy products
Palm and coconut oil
|Commercially baked pastries, cookies, doughnuts, pizza dough
Packaged snack foods
Here are a few other fat types you should know about:
The Omegas: You must have heard about the omega-3s and omega-6s. These are healthy fats and should generally be consumed in a ratio of 1:1 (omega-6 to omega 3).
However most people consume more of omega 6, which is unhealthy. Omega-3s are found in things like fish, nuts and types of algae. Omega-6s are found in grains, corn, and animals fed grains and corn.
Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are healthy omega 3 fatty acids that help in brain function. Alpha-linolenic acid (ALA) comes from plants and is a less potent form of omega-3.
Interesterified Fats: These are savoury fats prepared as a substitute for trans fat. They convert oil into fat and the process involved renders a product trans fat free but produces many harmful substances which make interesterified fats as harmful as trans fat.
They cause similar health hazards as trans fats and are mentioned on food labels as high stearate or stearic rich fats or some other confusing name.
Note: Unsaturated fats and the omegas are healthy fats. Saturated fats found in nature can be consumed in moderate amounts. Trans fats are the real bad guys which you should be avoiding at any cost.
How do fats affect your body weight?
Based on scientific logic it is difficult to propose that fats make you fat. Overconsumption of fats or any other dietary nutrient leads to weight gain. Trans fat or processed fats can make you fat.
Replacing fats with carbohydrates is another cause of weight gain.
However fats are a source of fuel to the body. If included appropriately in the diet they can actually aid in weight loss in the following manner.
1. Eating fats burns fat
Like any other dietary component, even fat plays a role in energy balance. The composition of fats affects their influence on body weight.
A study was organized wherein volunteers were given 60% of energy as fat. The oils tested were olive oil, sunflower oil and flaxseed oil. Meals prepared in olive oil showed increased energy expenditure or burning of calories than sunflower or flaxseed oil. Oils rich in oleic acid like olive increase metabolism and fat oxidation.
Decrease in palmitic acid stimulates metabolism. However increase in palmitic acid does the reverse. It is found in poultry, beef, dairy fat and palm oil. Replacement of palmitic acid with oleic acid increases resting energy expenditure or metabolism.
In a clinical trial three high fat meals were tested for their effect on energy expenditure. The diets were as follows:
- high in polyunsaturated fatty acids from walnuts
- high in monounsaturated fatty acids from olive oil
- high in saturated fatty acids from fat-rich dairy products
Thermogenesis (production of heat by processing food; a way to burn calories) was 28% higher in PUFA and 23% higher in MUFA than saturated fats.
High vegetable fats intake is associated with high metabolism rate. Long term consumption of medium chain triglycerides oil (naturally found in coconut oil, palm kernel oil and milk fat) brings about increased oxidation of fats and elevated metabolism rates in comparison to long chain triglycerides.
What does this mean?
Consuming fats promotes fat oxidation and can aid in weight loss.
2. Fats control appetite and make you full
Foods rich in fats have favourable palatability which then raises the question of overeating. A clinical trial was conducted to evaluate effect of high fat meal on hunger and appetite responses.
High fat meals were designed such that 70% of the energy was from fat and the different fat types included were MUFAs, PUFAs and saturated fatty acids. Saturated fatty acids exerted the highest control on appetite followed by PUFA and MUFA.
Another study investigating various functional foods and their control on appetite suggested that nuts which are rich source of dietary fats , have a satiety inducing effect when used to replace isocaloric food items.
Dietary fats help to control appetite by influencing various hormones and proteins. It decreases the level of ghrelin (hunger hormone), glucagon peptide-1 (a protein that prolongs gastric emptying thus contributing to a satiety effect) and decreases PYY (a protein that reduces appetite).
Low fat diets favourably modify leptin levels which is a hormone that controls appetite and stimulates fat burning. Oleoylethanolamide is a molecule produced in small intestine that promotes satiety after meals and research proves that dietary fat can favourably stimulate its intake.
What does this mean?
Dietary fats modulate various hormones and proteins that influence satiety.
3. Eating fats means reducing carbs
Eating fast translates as eating less carbs and vice versa. As mentioned previously fats and carbs serve as fuel for the body. So when you are eating less carbs and more fat you are stimulating your body to make use of dietary fats as well as fat reserves.
Also circulating insulin levels are reduced when less carbs are consumed. And we know that insulin levels do not only control glucose levels but also regulate fat utilisation and storage.
So low circulating insulin levels promote utilisation of fat as fuel and support burning of calories.
Refined carbohydrates have a worse impact on metabolic features than saturated fats. Replacing saturated fats with monounsaturated fats reduces the risk of heart diseases in a far better way than replacing them with carbohydrates.
4. Fat consumption makes you happy and helps you to adhere to a diet
This is the reason why low fat foods cannot help in controlling our cravings for fatty foods, thus paving the way for binge eating and emotional eating.
That is why it gets so difficult to stick to low fat diets. A study was conducted to investigate the effect of plain low fat yogurt and low fat yogurt mixed with a fat free aroma extract of olive oil on parts of the brain that respond to taste sensations.
The low fat yogurt supplemented with olive oil aroma extract increased the blood flow to the part of the brain linked with gustatory or taste sensation system. This clearly indicates that low fat items do not satisfy our desire for fatty foods as they lack the taste.
However this interaction of fats with the brain’s rewarding system can prove to be dangerous when it causes overeating. So it’s preferable to eat healthy fats so that you enjoy the taste without the risk of gaining weight.
5.Fats builds muscle mass
Eating healthy fats can help develop muscle mass. A clinical trial investigated the effect of supplementing individuals of age 25-45 years with polyunsaturated fatty acids and the PUFAs demonstrated an anabolic or muscle building effect on them.
PUFAs have a positive effect on bone and muscle mass preservation. Other studies also provide evidence that dietary fats especially polyunsaturated fats can help in preserving muscle mass. Very low carbohydrate diets which are rich in fats and proteins also are proven to aid in muscle mass preservation.
This is highly advantageous for weight loss as the ideal weight loss is loss of fat free mass and preservation of muscle mass.
Note: Fats if consumed at moderate amounts aid in weight loss by burning calories and controlling appetite. They also prevent loss of muscle mass.
Low fat diets- Why they didn’t work?
Low fat diet was a trend started by nutritional committees back in 1970s. They were recommended on the grounds that saturated fats increase cholesterol levels and increase the risk of obesity.
However the exact opposite occurred. Rates of obesity increased tremendously after the onset of low fat diets. A study clarifies as to why this occurred:
Reduction of dietary fat brought only small decrease in body weight.
Although calories from dietary fat were reduced, total calories were not reduced. In fact total caloric intake was increased.
Consumption of fats was replaced by consumption of carbohydrates especially refined sugars and products containing high fructose corn syrup which increase body weight.
Overall people were fooled into believing that fats made them fat, actually it was depleting them of vital source of energy and nutrients.
Sucrose Polyester- A non-caloric fat
Sucrose Polyester was developed by Proctor & Gamble scientists. It is a synthetic mixture of sugar and vegetable oil.
It is a sucrose molecule which has fatty acids attached to it. It has physical properties similar to triglycerides and is therefore used to substitute fats in snacks.
The fatty acids protect the core so strongly that it is resistant to digestion in the intestinal tract. Therefore it passes unabsorbed in the digestive tract and hence it is a non caloric fat. Sucrose polyester goes by the name Olestra or Olean.
Research proves that as a fat substitute it can be utilised to lower cholesterol levels, reduce weight, control appetite and so on. When used to substitute dietary fat, it mediates weight loss by promoting satiety, reducing calorie content, lowering cholesterol and providing same taste as high fat diet.
So this molecule would seem like an answer to your prayers as a replacement for trans fat. But everything comes with a catch.
In 1996, the FDA approved olestra for use in savory snacks such as chips, crackers, and tortilla chips, with a label that stated: ‘This Product Contains Olestra. Olestra may cause abdominal cramping and loose stools. Olestra inhibits the absorption of some vitamins and other nutrients. Vitamins A, D, E, and K have been added’
Yes Olestra can cause some gastrointestinal problems and also reduce absorption of vitamins which is why by 2000 sales of products containing Olestra declined. But you can still find some products containing Olestra marketed in some countries. Sucrose polyester now finds its use as an industrial lubricant and paint additive.
Since you can’t replace or avoid fats, so where can you find healthy fats?
Now that we have told you so much about fats and which are the good guys we might as well tell you where to find them.
Coconut oil: It has a good blend of saturated fatty acids and unsaturated fatty acids. A study where 12 week supplementation of coconut oil brought about a reduction in abdominal obesity in women.
Olive oil: This is the prime reason why a Mediterranean diet keeps you lean and reduces the features of metabolic syndrome.
Avocado: It is highly nutritious food rich in vitamins, minerals and low in saturated fat. Scientists have proven that is not a fattening food by demonstrating how its intake does not disturb the weight loss outcomes of an energy restricted diet.
Salmon: This fish is extremely popular in the culinary world and research proves that omega 3 fatty acids present in this fish help in weight loss and reducing inflammation. (Read more: Fish & Weight loss Salmon & Weight loss)
Grass fed beef: Meat obtained from grass fed cattle have high nutritional value and are said to increase PUFA in consumer’s system. And we know PUFAs mean weight loss. (More info available here: Meats & Weight loss)
Nuts : All nuts are rich sources of dietary fat and they aid in weight loss by controlling appetite.
Few ways by which you can reduce saturated fat in your diet are:
- Replace red meat with white meat such as fish and chicken.
- Choose healthy cooking oils like olive oil and coconut oil.
- Bake and boil instead of frying especially deep frying.
- Go for lean cuts of meat.
- Avoid liquid vegetable oils.
How much fat should you take for weight loss?
American Heart Association makes the following recommendation with respect to dietary fat intake:
- Fats should account for 25-35% of your total calories.
- Saturated fats should be around 7% or less of your total daily calories. So for a 2000 daily calorie requirement it would be around 140 calories or 16 grams.
- Trans fat should be 1% of your total daily calorie intake. That would be 20 calories or 2 grams for a 2000 calorie requirement.
- Majority of fats consumed should be monounsaturated and polyunsaturated fats.
With this article we have busted many myths like all fats are same and fats make you fat or fats lead to high level of cholesterol or heart diseases.
It is extremely important to consume fats as it serves as an energy source and helps in the storage and function of vitamins.
Keep mind that it is the healthy fats that you need and not the bad ones. More importantly whatever our weight related goals may be, we should always aim for a complete, well balanced diet.