Metabolic response phases

The metabolic response is characterized by four phases:

• Protein anabolism.

1. The injury phase. This lasts 5 to 7 days. During the first 2 days, there are large hormonal changes with an increase in catecholamine and corticosteroid levels, and an initial decrease in the level of insulin. These hormonal changes are thought to be stimulated by the release of numerous cytokines such as interleukin. The result is muscle, fat, and glycogen store catabolism, liberating substrates such as glucose, lactose, proteins and free fatty acids (FFA). These are important for energy, plasma protein formation, immune response and wound repair. The nitrogen balance is negative and albumin levels fall, while cardiac output, oxygen usage and energy consumption are high in proportion to the severity of the trauma. Energy consumption is increased by 20% in a single long bone fracture and by >50% in a burns victim. Water and sodium are in positive balance and potassium in negative balance, due to changes in antidiuretic hormone (ADH) and aldosterone levels.

In the next 5 days (the flow phase), catecholamine levels continue to be high, but the insulin level increases and protein breakdown slows, with glucose directed at wound healing.

2. The turning point phase. This occurs from approximately the fifth to the tenth day, with a reversal of hormonal influences, a change to an anabolic state with positive nitrogen and potassium balance, and negative water and sodium balance.

3. Protein anabolism phase. This phase may last 4 to 5 weeks, as corticosteroid levels normalize and growth hormone levels increase. Plasma protein (such as albumin) levels rise and muscle is restored.

4. Fat anabolism phase. The final phase is slower and prolonged over several months. Insulin stimulates lipogenesis, as fat stores and body weight are regained.

Boost Your Metabolism and Burn Fat

Boost Your Metabolism and Burn Fat

Metabolism. There isn’t perhaps a more frequently used word in the weight loss (and weight gain) vocabulary than this. Indeed, it’s not uncommon to overhear people talking about their struggles or triumphs over the holiday bulge or love handles in terms of whether their metabolism is working, or not.

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