Do I Need to Fast? What about Coffee and Water?

2 min read

8/13/26

Key Takeaways

Fasting isn't mandatory for every marker, but it makes triglycerides and calculated LDL far more comparable month to month.
Water is encouraged, hydrate normally, plus a glass 30–60 minutes before collecting.
Whatever you choose (fasted or not, coffee or not), consistency across tests matters most.

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Using Rythm

Do I Need to Fast? What about Coffee and Water?

2 min read

8/13/26

Key Takeaways

Fasting isn't mandatory for every marker, but it makes triglycerides and calculated LDL far more comparable month to month.
Water is encouraged, hydrate normally, plus a glass 30–60 minutes before collecting.
Whatever you choose (fasted or not, coffee or not), consistency across tests matters most.

Fasting

Not required for every biomarker, but eating shifts triglycerides, remnant cholesterol, calculated LDL-C, and triglyceride-based ratios. For the cleanest longitudinal comparison across Rythm's panel, collect under the same fasting conditions each time; a morning fasted draw is the most standardized option.

Water

Yes, please. Hydration supports blood flow and makes the tube easier to fill. Rather than chugging right before collection, hydrate normally and have water about 30 to 60 minutes beforehand.

Coffee

For a strictly fasting collection, water only, coffee can nudge stress hormones, metabolism, heart rate, and hydration, and cream or sugar clearly breaks a fast. If you regularly collect after coffee, the important thing for trend tracking is not switching unpredictably between coffee and no coffee.

Alcohol

Alcohol can significantly affect triglycerides, hydration, glucose regulation, inflammation, and liver-associated markers like GGT. Skipping it the night before gives you a cleaner baseline, especially worth it if you're trying to understand an unexpected triglyceride or GGT result.

Frequently Asked Questions

How is Rythm different?

Most blood testing companies charge $500 or more for a single test per biomarker, providing only a one-time snapshot that doesn’t capture your long-term health trends or reflect your true baseline. This approach can lead to missed patterns or even misdiagnoses due to limited data. Rythm takes a different approach, using monthly tracking to build a detailed picture of your health over time. This allows for more accurate insights, better optimization, and a clearer understanding of how your body is evolving.

Does Rythm help me improve?

Rythm provides actionable suggestions and tips to help you optimize each biomarker

Is Rythm HIPAA compliant?

Yes, Rythm is HIPAA compliant. Your data is securely stored and handled in accordance with strict privacy and security standards.

Can I cancel anytime without fees?

Yes, you can cancel anytime without any fees.

Does Rythm accept HSA/FSA payments?

Yes, Rythm is HSA/FSA eligible. You can use your HSA or FSA card at checkout or submit your Rythm receipt to your provider for reimbursement.

How long does it take to get my results?

You will receive your results within 3 business days – as long as it's returned within 7 days of receiving your kit. Delays can occur if you do not send your sample back in time.