Tuesday, August 19, 2014

Can you eat the “right fats” and still lose weight?

Although the word “fat” has been a source of anxiety to most people, and often accused for overweight and obesity, fats vitality to health is big! And you don’t have to go on low fat diet to lose weight, only by consuming right amounts and the right type of fats, as you will see next.


What are Fats?

Fats (or lipids) are a family of organic compounds (compounds that are made of carbon (C), hydrogen (H), and oxygen (O) atoms) characterized by their insolubility in water. 

Along with carbohydrates and protein, dietary fats are macronutrients -meaning that the body needs it in large amounts compared to other essential nutrients- and it is a major source of energy in our diet. When metabolized in the body; fat produce 9 Calories whereas carbohydrate and protein produce 4 Calories.



Why you should get your dietary fats?                                                                        

Dietary fat is vital to health since it is:

  • An important source of energy,
  •  Solvent and medium of transfer for vitamin A, D, E, and K,
  •  Provides building blocks for creating new cells, especially cell membranes,
  •  Involved in regulation of cell functions,
  •  source of essential fatty acids (omega 3 & omega 6),
  •  supports body’s growth and development,
  •  plus, it improves the taste and texture of food.

 

How much to eat from fat?

According to the CDC (center of diseases control and prevention) it is recommended that adults (19 years and older) consume 20% to 35% of total calories from fat, and 25% to 35% for adolescents & children above 4 years old. Generally; people tend to consume more fat than the recommended amount which contributes to the occurring of cardiovascular diseases.



What to eat from fat? Good fats vs. Bad fats                                 

For the past couple of years, it has been the question of what fats to eat more than how much fat to eat, that’s due to the impact of types of fats consumed on health.

Based on the main fatty acid types (witch you will get to know as you keep reading this article) present in a fat source and their impact on health; fats are categorized into: good fats (that you should focus on incorporating in your diet) and bad fats (that you should limit and avoid as possible in your diet)

Dietary Fats

Fat type

Impact on health

Main food sources

Good fats

(focus on choosing more of these)

PUFA

Poly unsaturated fatty acids

Reduce LDL and increase HDL, include essential fatty acids omega-3 & omega-6 that contribute to normal growth, metabolism, and brain function, among others things.

Omega-3 also has anti-atherogenic effect.

- omega-6 , sunflower, sesame, safflower and corn oil, nuts, seeds, non- hydrogenated margarines

- omega-3: flax seed, fish, walnuts, canola and soybean oils

MUFA

Mono unsaturated fatty acids

Improves blood cholesterol levels, and may benefit insulin levels and blood sugar control, which can be helpful for type 2 diabetes patients.

Olive, avocadoes, nuts and seeds, canola and peanut oil

Bad fats

(limit consumption)

SFA (saturated fatty acids)

They raise total blood cholesterol levels and low-density lipoprotein (LDL) cholesterol levels, which can increase risk of cardiovascular disease, may also increase risk of type 2 diabetes.

Butter, hydrogenated oils, coconut oil, palm kernel, cocoa butter

Trans FA

They are associated with elevated blood LDL cholesterol, a pro-atherogenic risk factor.

Shortening, hydrogenated vegetable oils, fast foods and ready to eat foods and bakery products.


Nutrition tips (Go for “good fats” not “no fats”)

Common foods high in good fats: fish (salmon and tuna), liquid vegetable oils (olive, canola, flax, etc.), nuts, beans and seeds.

Common foods high in bad fats: anything with “trans-fat written on its label commercially-baked goods, high saturated-fats content foods (ice cream, processed meats and some types of cheese)

 

Focused lens on: Types of Lipids

Among the many compounds classified as lipids, we’ll be discussing fatty acids, triglycerides, sterol and lipoproteins, due to their importance to health.


- Fatty acids

Fatty acids are chains of carbon atoms with hydrogen attached, that has acid group (COOH) at one end and a methyl group (CH₃) at the other end, and they are the simplest form of lipids.

Fatty acids differ from each other in two ways:

  • The length of fatty acid: depending on the number of carbons in the chain in even number up to 24 carbons; with long chain fatty acids (12-24 carbons) in meats, fish and vegetable oils being the most common in foods. And medium chain (6-10 carbons) and short chain (less than 6 carbons) fatty acids mainly in dairy products.
  • The number of double bonds (degree of unsaturation): they are classified into: Saturated, monounsaturated and polyunsaturated fatty acids.


Saturated fatty acids (SFA) have no double bonds between carbon atoms and are rigid molecules; monounsaturated fatty acids (MUFA) have a single double bond, while polyunsaturated fatty acids (PUFA) have two or more double bonds. More points of unsaturation make the lipid more fluid at room temperature.


Another difference is the configuration of the double bond: cis or trans configuration. In cis form, the fatty acid folds back, forming a U-shape orientation whereas in trans form, the effect is extending the molecule into a linear shape similar to that of a SFA in shape and properties.

The cis configuration is most naturally occurring, although trans configuration also occurs naturally in some foods; the large majority of trans fatty acids are derived through a process known as hydrogenation (which is a process by which some or all of the points of unsaturation are saturated, making fats more solid to protect them against rancidity, and producing trans-fats).


- Triglycerides

Triglycerides (TG) are lipids composed of three fatty acids attached to a glycerol molecule, they occur as liquid oils or solid fats at room temperature depending on the degree of saturation and length of fatty acids they have. The more the unsaturation and the shorter the fatty acids the more liquid the lipid is at room temperature.


- Sterols

Sterols are multiple-ring structured lipids; they take part in bile acids, sex hormones, adrenal hormones and vitamin D. They are derived from both plant and animal sources, with Cholesterol being the most famous sterol. Know more in All about Cholesterol.


- Lipoproteins

Lipoproteins are clusters of lipids (mainly cholesterol and TG) associated with proteins that work as vehicles for transportation of lipids in the lymph and blood since the lipids are not soluble in the aqueous blood.

Depending on the ratio between lipid and proteins (the higher the protein ratio the higher the density of the lipoprotein); lipoproteins are classified into:

  •  Chylomicrons (with the lowest density i.e. low protein ratio)
  •  Very low density lipoprotein (VLDL)
  •  Low density lipoprotein (LDL)
  •  High density lipoprotein (HDL) with the highest density i.e. high protein ratio)

Chylomicrons are responsible for transporting TG from intestines to tissues, LDL is responsible for making TG available to tissues (including the heart muscle), whereas HDL removes cholesterol from cells to the lives for recycling or disposal. That why having higher HDL, level is good to protect against cardiovascular diseases (CVD).

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