Energy Provision at Rest
Energy provision at rest is the metabolism without physical load: how much energy the body expends and from which mix of fats and carbohydrates it comes.
Definition
“Energy provision at rest” describes how the body obtains energy without physical load. Two questions are central: how much energy is expended (resting metabolic rate) and which substrates it comes from (fats or carbohydrates).
The underlying pathways are described in the entry “Energy Provision in the Body”; the counterpart under exercise is found under “Energy Provision under Load”. At rest, energy production is practically entirely aerobic.
Why it matters
The common assumption is that at rest the body burns mostly fat, because energy demand is low and plenty of oxygen is available. For a rested, healthy organism this is usually true, with a respiratory quotient (RQ) around 0.75 to 0.82.
For an individual, however, it is anything but certain. Chronic stress, sleep deprivation, infections, healing after injury, or a very carbohydrate-rich diet can lead the body to burn predominantly carbohydrate even at rest. A resting RQ of 0.90 means fat oxidation is already suppressed in the baseline state, and that continues under load.
| Resting RQ | Fat share | Typical situation |
|---|---|---|
| 0.72–0.78 | 75–95 % | Rested, fasted, well-adapted fat metabolism |
| 0.79–0.85 | 50–70 % | Normal range |
| 0.86–0.92 | 25–45 % | Stress, shortly after a carbohydrate-rich meal, overtraining |
| above 0.92 | below 25 % | Acute strain on the organism, infection, hyperventilation |
How obseed measures it
Resting metabolism cannot be calculated, only measured. Formulas such as Harris-Benedict estimate resting energy expenditure from age, weight, and height with errors of up to 20 % and say nothing about the substrate mix.
obseed therefore uses the resting measurement from spiroergometry: 10 to 20 minutes lying down in a fasted state, recording oxygen uptake (VO2), carbon dioxide output (VCO2), breathing rate, tidal volume, and heart rate. From these come resting energy expenditure in kcal/day and the RQ as a measure of the substrate mix.
In addition, obseed draws on daily resting heart rate and HRV from overnight measurement. If resting heart rate rises above baseline while HRV falls at the same time, that is a sign the resting metabolism has shifted towards carbohydrate, before the next test is due.
Example
An athlete, 62 kg, is measured fasted at rest: VO2 0.24 l/min, VCO2 0.19 l/min.
| Measure | Calculation | Result |
|---|---|---|
| RQ | 0.19 / 0.24 | 0.79 |
| Energy expenditure per minute | 0.24 × 4.85 kcal/l | 1.16 kcal/min |
| Resting expenditure per day | 1.16 × 1440 | approx. 1,680 kcal |
| Fat share at RQ 0.79 | Table | approx. 70 % |
| Fat oxidation at rest | 1.16 × 0.70 / 9.4 | 0.086 g/min |
The Harris-Benedict formula would have given her around 1,420 kcal/day, 260 kcal too low. Six months later, after a period of heavy work stress, the repeat measurement shows an RQ of 0.88 at the same expenditure. The fat share has dropped to about 40 %, a finding that directly shapes the plan for the next base block.
Categories
- Diagnostik
- Technische Begriffe