How are lipids obtained?

January 14, 2026 •

4 min read

Approximately 95 percent of all dietary fats are triglycerides, a major type of lipid, but your body doesn't rely on diet alone to get its lipids. The human body obtains lipids from two main sources: through the digestion of dietary fats and via internal synthesis within the body itself.

Quick Summary

Lipids are acquired from dietary intake, primarily triglycerides from food, and from endogenous synthesis in the body's liver and adipose tissue. This dual pathway ensures a constant supply for energy, hormone production, and cell structure, with the body regulating its internal production based on dietary consumption.

Key Points

Dual Acquisition: The body obtains lipids from two main sources: dietary consumption (exogenous) and internal synthesis (endogenous).
Dietary Triglycerides: The vast majority of lipids in our diet are triglycerides, found in fats (animal products) and oils (plant sources like olives and nuts).
Endogenous Synthesis: When energy intake exceeds demand, the body converts excess carbohydrates into lipids via lipogenesis, primarily in the liver.
Essential Fatty Acids: The body cannot produce essential fatty acids like omega-3 and omega-6, which must be obtained from dietary sources such as fatty fish, nuts, and seeds.
Storage and Mobilization: The body stores lipids as triglycerides in adipose tissue and can break them down into fatty acids for energy when needed through lipolysis.
Cholesterol Homeostasis: While some cholesterol comes from the diet, the liver produces most of what the body needs, regulating synthesis based on intake.

Dietary Sources of Lipids

Dietary lipids, known as exogenous lipids, constitute a significant portion of our daily energy intake and provide essential fatty acids that the body cannot produce on its own. Lipids are a diverse group of compounds, but the most common dietary lipids are triglycerides, followed by phospholipids and sterols like cholesterol.

Types of Dietary Lipids

Triglycerides: Commonly known as fats and oils, these make up the majority of lipids we consume. Fats are typically solid at room temperature and come from animal sources like butter, meat, and dairy, while oils are liquid and sourced from plants such as olives, nuts, and avocados.
Phospholipids: These are crucial components of cell membranes and are synthesized within the body, though they also make up about 2% of dietary lipids. They are found in both plant and animal foods.
Sterols: Cholesterol is the most well-known sterol. While the body produces most of its own cholesterol in the liver, some is obtained from animal-based foods like egg yolks, cheese, and shrimp.

Digestion and Absorption

The journey of dietary lipids through the body is a complex process designed to handle their water-insoluble nature.

Mouth: Chewing mechanically breaks down food, and the enzyme lingual lipase begins minor chemical digestion.
Stomach: Churning motions and gastric lipase continue the breakdown of triglycerides into diglycerides and fatty acids.
Small Intestine: This is where the majority of digestion occurs. The presence of fat stimulates the release of bile from the gallbladder, which emulsifies large fat globules into smaller droplets, increasing the surface area for enzymes to act. Pancreatic lipase breaks triglycerides down into fatty acids and monoglycerides.
Micelles: The products of digestion, along with bile salts, form micelles, which transport the lipids to the intestinal wall for absorption.
Chylomicrons: Inside the intestinal cells, triglycerides are reassembled and packaged with cholesterol into large lipoproteins called chylomicrons. These chylomicrons are released into the lymphatic system and eventually enter the bloodstream for transport to tissues, including the liver and adipose tissue.

Endogenous Synthesis (Lipogenesis)

In addition to dietary sources, the body can produce its own lipids, particularly in the liver and fat cells (adipocytes). This process, known as lipogenesis, primarily occurs when there is an excess of energy from carbohydrates or protein. Excess glucose is converted into the molecule acetyl-CoA, which serves as the building block for fatty acids and other lipids.

The Process of Lipogenesis

Location: Primarily occurs in the cytoplasm of liver and fat cells.
Precursor: Excess carbohydrates lead to abundant acetyl-CoA via glycolysis.
Synthesis: Acetyl-CoA is converted into fatty acids and then combined with glycerol to form triglycerides. Acetyl-CoA is also used to synthesize other lipids, including cholesterol and steroid hormones.

Lipid Storage and Mobilization

Once obtained, lipids are stored in the body for future use. The primary storage form is triglycerides, which are held within adipocytes in adipose tissue. This tissue can expand to accommodate significant amounts of stored fat, making lipids an incredibly efficient long-term energy reserve. When the body requires energy between meals or during fasting, it mobilizes these stored lipids through a process called lipolysis.

Mobilization of Stored Lipids

Lipolysis: This is the breakdown of stored triglycerides into glycerol and free fatty acids.
Transport: The free fatty acids are released into the bloodstream and travel to energy-demanding tissues, such as muscles.
Oxidation: In the mitochondria of cells, fatty acids undergo beta-oxidation to produce acetyl-CoA, which then enters the Krebs cycle to generate large amounts of ATP.

Comparison of Lipid Sources


Feature	Dietary (Exogenous) Lipids	Endogenous (Synthesized) Lipids
Origin	Ingested via food	Produced within the body
Primary Location	Digested in small intestine	Synthesized primarily in the liver
Regulation	Digestion regulated by enzymes and bile salts; synthesis is suppressed with high intake	Synthesis is increased when excess calories are available, especially from carbohydrates
Types Obtained	All essential fatty acids; various triglycerides, phospholipids, and some cholesterol	Non-essential fatty acids, triglycerides, cholesterol, and steroid hormones
Transport Method	Packaged into chylomicrons	Transported via VLDL lipoproteins from the liver

Conclusion

The body's ability to obtain lipids from both dietary intake and internal synthesis provides a robust and flexible system for managing energy needs. Dietary lipids supply essential fatty acids and a quick source of energy, while endogenous synthesis allows for the efficient storage of excess calories for future use. The two pathways are interconnected and regulated by feedback mechanisms to maintain lipid homeostasis. A balanced diet and healthy metabolism are crucial for ensuring the body has the right amount and type of lipids for all its vital functions. For more information on lipoprotein metabolism, a key aspect of how the body handles these lipids, you can consult this resource from NCBI Bookshelf.

Frequently Asked Questions

Dietary lipids are obtained from the foods we eat, while endogenous lipids are synthesized internally by the body, predominantly in the liver.

No, the body cannot create essential fatty acids, such as omega-3 and omega-6, and must obtain these important lipids from the diet.

Excess lipids are primarily converted into triglycerides and stored in specialized fat cells called adipocytes, which make up adipose tissue.

Dietary fats are first broken down in the mouth and stomach by lipases, but most digestion occurs in the small intestine, where bile emulsifies them and pancreatic lipase further breaks them down for absorption.

Lipogenesis is the process by which the body synthesizes lipids, such as fatty acids and triglycerides, from excess energy sources like carbohydrates.

The body, especially the liver, synthesizes the majority of the cholesterol it needs. Only a small portion is obtained from dietary sources.

When the body needs energy, it breaks down stored triglycerides into fatty acids and glycerol through a process called lipolysis, which are then used to produce ATP.