What is CLA and How Does It Work?
Conjugated linoleic acid, or CLA, is a naturally occurring fatty acid predominantly found in meat and dairy products from ruminant animals. In its supplement form, CLA is typically derived from vegetable oils, such as safflower oil, and is composed of a mixture of isomers,. The two most researched isomers are cis-9, trans-11 (c9, t11) and trans-10, cis-12 (t10, c12), which are believed to have different effects on the body.
The Mechanisms of Action
CLA's purported effects on body composition are primarily attributed to its influence on fat metabolism,. The t10, c12 isomer, in particular, is thought to:
- Increase Lipolysis: Stimulate the breakdown of stored fat cells.
- Inhibit Adipogenesis: Decrease the creation of new fat cells.
- Increase Energy Expenditure: Boost the body's basal metabolic rate, potentially leading to more calories burned at rest,.
These mechanisms suggest a role in reducing body fat mass and potentially improving lean muscle mass, though human study results have been mixed and often show modest effects,.
The CLA and Sleep Connection
For many, the idea of a supplement that helps burn fat while they sleep is an appealing prospect. Research has explored this exact concept. A specific study mentioned in multiple sources showed that overweight adults who took CLA experienced an increase in fat oxidation and energy expenditure during sleep after six months of supplementation,. This suggests that CLA's metabolic effects can, for some individuals, be active during the nocturnal hours.
Interpreting the Results
- The Positive: Increased fat oxidation during sleep could contribute to long-term body composition changes, as the body uses fat for fuel while resting. This is a key reason some people consider a nighttime dosage.
- The Caveat: The overall weight loss effects of CLA in humans are generally modest. This means that while there might be a measurable metabolic effect during sleep, it may not translate into dramatic or rapid weight loss in the real world. Additionally, the study used a specific blend of isomers and a particular dose (3.2g/day), and not all CLA products are the same.
Potential Side Effects and Your Sleep
While the metabolic effects during sleep seem promising, it's crucial to consider potential side effects that could disrupt a good night's rest. Several sources indicate that CLA supplementation, especially in larger doses, can cause gastrointestinal discomfort,,.
Common side effects include:
- Stomach upset
- Nausea
- Diarrhea
- Fatigue
These symptoms can be disruptive to sleep, particularly nausea or stomach cramps. Fatigue is another noted side effect, but its effect on sleep quality could vary by individual. It's also important to note that the fatigue mentioned in some sources could relate to overall daytime energy levels rather than a direct effect on sleep initiation.
Optimal Timing and Dosage
Most nutritional experts recommend taking CLA with meals to improve absorption and minimize gastrointestinal distress,. This can be broken down into a few practical approaches:
- Morning/Daytime Split: Taking one dose with breakfast and one with lunch or dinner is a common strategy. This ensures consistent intake throughout the day while potentially avoiding any sleep disruption caused by gastrointestinal issues.
- Evening With a Meal: If you prefer to dose in the evening, taking it with your dinner is a better strategy than on an empty stomach right before bed. This can still allow for the nocturnal metabolic effects without the risk of stomach upset interfering with sleep.
Common Dosage: Most studies that showed some efficacy used doses between 3 and 6 grams per day. It is generally advised to start at a lower dose and increase gradually to assess tolerance. Doses above 6 grams per day are not recommended and may increase the risk of side effects.
Comparison: Taking CLA Before Bed vs. With Meals
| Feature | Before Bed (Empty Stomach) | With Meals (Day or Evening) |
|---|---|---|
| Absorption | Can be less effective; potential for stomach upset is higher. | Improved absorption and better tolerability due to being taken with food. |
| Nocturnal Effects | Maximizes potential for increased fat oxidation during sleep. | Likely still benefits from metabolic activity during sleep, but initial absorption occurs earlier. |
| Side Effects | Increased risk of gastrointestinal issues like nausea, diarrhea, and stomach upset, which can disturb sleep. | Reduced risk of stomach discomfort; can mitigate potential digestive side effects. |
| Safety | Less ideal, especially for those with sensitive stomachs or a history of digestive issues. | The standard and safest recommendation for CLA supplementation. |
Who Should Be Cautious About Taking CLA at Night?
While CLA is considered safe for most people in recommended doses, certain individuals should exercise caution, especially with evening intake. This is particularly relevant for those prone to digestive issues or who find that supplements affect their sleep quality.
- People with sensitive stomachs: Those who experience nausea, bloating, or diarrhea with other supplements should avoid taking CLA late in the evening to prevent sleep disturbance.
- Individuals on medication: Anyone taking medication, particularly blood thinners or blood pressure drugs, should consult a doctor before starting CLA, as it can interact with some treatments,.
- Diabetics or those with metabolic syndrome: Some studies suggest CLA can worsen insulin resistance, especially with high doses over a long term,. This is a critical consideration and requires medical supervision.
For most people, taking CLA with meals throughout the day is a well-tolerated and standard approach that still allows for potential metabolic benefits without the added risk of nocturnal side effects.
Conclusion: Can You Take CLA Before Bed?
Yes, you can take CLA before bed, and some studies suggest it may boost fat oxidation during sleep. However, the optimal and most widely recommended approach is to take it with meals to maximize absorption and reduce the risk of gastrointestinal side effects,. Given the potential for side effects like stomach upset or nausea, which could interfere with sleep, taking CLA on an empty stomach right before bed is not advisable for most individuals. Ultimately, while the timing might offer a slight edge in nocturnal metabolism, a consistent dosage taken with meals is likely the safest and most effective strategy for the long-term, modest body composition changes associated with CLA supplementation.
An outbound link to learn more about the complexities of conjugated linoleic acid and its effects can be found in this publication: https://pmc.ncbi.nlm.nih.gov/articles/PMC2826589/.
