Triglycerides in Athletes: Why Low Values Are a Sign of Metabolic Fitness
Table of Contents
Introduction
In clinical practice, I often interpret triglycerides in athletes through a familiar principle: when we want to improve a patient’s lipid profile, regular exercise is one of the first lifestyle tools we recommend, usually alongside a healthier dietary pattern. Athletes often represent the far end of that same physiological spectrum. Their lipid profiles are generally more favorable than those of sedentary individuals, and in my own clinical work, it is relatively uncommon to see physically active athletic patients requiring lipid-lowering medication compared with the broader patient population. In endurance athletes, this favorable metabolic profile can include fasting triglyceride values that appear unusually low when judged against standard population reference ranges.
For that reason, low triglycerides in athletes should not automatically be seen as an abnormal finding. In many cases, they are better understood as part of a broader training-related metabolic profile. Understanding why triglycerides in athletes are low is not merely an academic exercise: it reflects adaptations in lipoprotein metabolism, skeletal muscle lipid handling, and, in some exercise-training contexts, hepatic lipid secretion.
In this article I examine the mechanisms behind training-associated low triglycerides in athletes, explains what “low” triglycerides mean in a clinical setting, and addresses the practical question clinicians and athletes often face: is this a sign of metabolic health, or a warning sign?
Why Standard Reference Ranges Do Not Apply to Triglycerides in Athletes
The National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) classifies fasting serum triglycerides as follows: normal below 150 mg/dL, borderline high 150–199 mg/dL, high 200–499 mg/dL, and very high at or above 500 mg/dL [1]. These are general adult clinical categories and are not athlete-specific.
In practice, many trained athletes never approach the “normal” upper boundary of 150 mg/dL. Seminal research compared 13 male endurance athletes with 12 sedentary men of matched age. The athletes had lower fasting triglycerides (75 ± 30.4 mg/dL v 125 ± 52.5 mg/dL) and higher high-density lipoprotein (HDL) cholesterol concentrations (64 ± 16.2 mg/dL v 42 ± 9.4 mg/dL) than the sedentary subjects (P < .01 for all) [2].
This pattern of lower triglycerides, often observed alongside higher HDL, has been reported in endurance-trained cohorts, although the magnitude and statistical significance vary between studies. For a detailed discussion of what elevated HDL values mean in athletic blood work, see the companion article on HDL cholesterol in athletes.
In my clinical work, triglyceride values outside the standard reference range are relatively uncommon among athletic patients, whereas elevated triglycerides are a much more familiar finding in sedentary patients with broader metabolic risk factors. This distinction is clinically important because triglycerides are often approached differently from LDL cholesterol. While statins have a clear central role in LDL-driven cardiovascular risk reduction, triglyceride management in everyday practice often begins with lifestyle measures: diet quality, weight management where relevant, alcohol reduction when appropriate, and regular physical activity. Medication can still be relevant in selected cases, especially when triglycerides are markedly elevated, but for many patients the first conversation is about nutrition and exercise. Triglycerides may also improve after statin initiation, although the main therapeutic target is usually LDL cholesterol and overall cardiovascular risk rather than triglycerides alone.
Mechanism 1: Accelerated Triglyceride Clearance
A key demonstrated contributor to low circulating triglycerides in athletes is accelerated removal of triglycerides from the bloodstream. The low TG levels in endurance athletes result at least in part from increased TG removal [2]. This was demonstrated mechanistically by measuring the plasma triglyceride clearance rate (K2) following an intravenous fat emulsion infusion. K2 in the athletes was 92% higher than that in the sedentary men (4.8 ± 2.3 %/min v 2.5 ± 0.7 %/min, P < .01), and K2 was inversely related to fasting TG concentrations (r = −.73, P < .01) [2].
This accelerated clearance has been associated with lipoprotein lipase (LPL) activity — particularly in trained women. A study comparing 12 female distance runners with 13 sedentary women showed that lipoprotein lipase activity (LPLA) was 33% greater (P < .05) and fat clearance (K2) was 27% faster (P < .01) in the trained women, and LPLA correlated directly with K2 (r = .61) and HDL-C (r = .62) in this group (P < .05 for both) [3].
Mechanism 2: Reduced Hepatic VLDL-Triglyceride Secretion
A second mechanism operates at the level of the liver. In addition to faster peripheral clearance, some exercise-training interventions have been shown to reduce the rate at which the liver secretes triglycerides into the circulation as very low-density lipoprotein (VLDL) particles. This was directly measured in a human training intervention using stable isotope-labeled tracer methodology in previously sedentary young men who underwent two months of supervised high-intensity interval training. Fasting plasma VLDL-TG concentration was reduced after training by ~28% (P ≤ 0.05), and this was due to reduced hepatic VLDL-TG secretion rate (by ~35%, P ≤ 0.05) with no changes (<5%, P > 0.7) in VLDL-TG plasma clearance rate [7].
Together, these studies suggest that exercise-related hypotriglyceridemia can arise through more than one mechanism: faster peripheral clearance in endurance-trained cohorts [2][3] and, in at least one short-term HIIT intervention in previously sedentary men, reduced hepatic VLDL-TG secretion [7].
Mechanism 3: Intramuscular Triglyceride Storage — The Athlete’s Paradox
A third mechanism involves where triglycerides go in a trained body. Endurance-trained muscle can contain higher intramyocellular lipid stores, which may serve as an exercise substrate. This has a counterintuitive clinical implication known as the “athlete’s paradox”: Dubé and colleagues previously reported an “athlete’s paradox” in which endurance-trained athletes, who possess a high oxidative capacity and enhanced insulin sensitivity, also have higher intramyocellular lipid (IMCL) content [5].
In sedentary obese populations, IMTG has been associated with insulin resistance. In trained athletes, the same elevated IMTG stores coexist with enhanced insulin sensitivity — a distinction explained by the higher lipid oxidation capacity of trained muscle.
This IMTG-insulin dynamic is closely related to the metabolic picture captured by HbA1c in athletes, where similarly counterintuitive findings emerge.
It is also important to remember that not every athlete has an ideal diet. Some physically active patients still have elevated triglycerides because of poor dietary patterns, excess alcohol intake, weight gain, high intake of refined carbohydrates, or broader metabolic risk factors. Exercise can partially compensate for these pressures, but in clinical practice it rarely compensates fully for a persistently poor diet.
Most of the time, however, the relationship works in the opposite direction: exercise and diet tend to support each other. When a patient becomes more active, they may also become more interested in nutrition, sleep, recovery, and other health behaviours. Similarly, better eating habits can improve training quality, body composition, and motivation to continue exercising. In that sense, lifestyle medicine is rarely about one isolated habit. Improvements in one area often create momentum in another.
From a clinician’s perspective, the practical challenge is often to help the patient become genuinely engaged with at least one part of the process. Sometimes that begins with exercise, sometimes with diet, and sometimes even with medication if it produces a measurable improvement that helps the patient feel that change is possible. When patients see concrete results — better laboratory values, improved energy, weight loss, better performance, or reduced symptoms — they are often more receptive to the next step in lifestyle change.
The Acute Exercise Effect: Postprandial Triglyceride Reduction
Beyond the chronic training adaptations, each exercise session can attenuate the postprandial triglyceride response. A 2022 meta-analysis and systematic review synthesised 279 effects from 165 studies. There was a moderate effect of exercise on the total TG response (Cohen’s d = −0.47; p < .0001) [4]. Moderator analysis revealed exercise energy expenditure significantly moderated the effect of prior exercise on the total TG response (p < .0001), and the attenuation of postprandial TG appears largely dependent on exercise energy expenditure (~2 MJ) and the timing of exercise [4]. The effect of prior exercise on the postprandial TG response appears to be transient; therefore, exercise should be frequent to elicit an adaptation [4].
This finding has a practical implication: training timing should be considered when interpreting an athlete’s lipid panel, as recent exercise may influence triglyceride-related measures.
In practice, lipid panels are often checked in the morning after an overnight fast, although in some laboratories, including in Finland, lipid tests may also be taken without fasting. When a fasting sample is used, athletes are rarely in a situation where they have trained immediately before the blood draw. This is partly practical: most fasting laboratory tests are taken early in the morning, and many athletes also know to eat after training to support recovery and avoid unnecessary catabolic stress. As a result, a true “trained hard, did not refuel, then came directly for fasting lipids” scenario is uncommon.
Still, it remains a possible confounder. If an athlete has trained unusually late the previous evening, exercised early before the blood draw, failed to refuel normally, or changed training volume in the days before testing, the lipid panel may not fully represent their usual baseline state. For clinicians, the practical point is simple: when interpreting triglycerides in athletes, it is worth asking not only whether the patient was fasting, but also when they last trained, whether they refuelled normally, and whether the recent training pattern was typical.
What Happens When Training Stops: Detraining and Rising Triglycerides in Athletes
The training-dependence of low triglycerides in athletes is most clearly demonstrated by detraining studies. A 2-year longitudinal study of previously highly endurance-trained subjects following cessation of physical activity showed that further disorders appeared in triglycerides (TG) metabolism during detraining, with a persistent increase in TG (from 1.0 ± 0.3 to 1.4 ± 0.3 mmol/liter), whereas glycerol decreased (from 88 ± 9 to 73 ± 8 µmol/liter) [6]. Plasma lipoprotein lipase activity decreased [6], confirming that LPL is a training-dependent adaptation that reverses with prolonged inactivity.
In general, this is also why I believe most patients should have some form of regular physical activity in their lives. The exact form does not have to be competitive sport, high-intensity training, or anything extreme. It may be walking, cycling, swimming, resistance training, recreational sport, or any other activity that the patient can sustain safely. But from a physiological perspective, the human body is not designed to do well without movement.
There are, of course, clinical situations where exercise has to be modified, paused, or supervised carefully. But in my view, true long-term exceptions are relatively uncommon. For most patients, the question is not whether they should move, but what kind of movement is safe, realistic, and meaningful enough that they will actually continue doing it.
A rise from an athlete’s established triglyceride baseline may therefore be compatible with reduced training or detraining, though the finding is nonspecific and should prompt review of training load and other clinical factors. This pattern connects to the broader metabolic regression seen with detraining discussed in the articles on cortisol in athletes and testosterone in athletes.
Conclusion
Low triglycerides in athletes are best understood as part of a broader training-related metabolic phenotype rather than as an isolated laboratory curiosity. In endurance-trained individuals, low fasting triglycerides can reflect faster triglyceride clearance, LPL-related lipid handling, skeletal muscle adaptations, and, in some exercise-training contexts, reduced hepatic VLDL-triglyceride secretion. At the same time, the interpretation should remain clinical rather than automatic: diet, alcohol intake, recent training, refuelling, illness, detraining, and the timing of the blood sample can all influence the result.
For clinicians, the most useful approach is often longitudinal. A single low triglyceride value in a healthy, well-trained athlete is usually consistent with favorable metabolic adaptation, whereas a sustained rise from that athlete’s own baseline may say more than whether the value still sits inside a population reference range. In my view, this is also one reason regular physical activity should be seen as a core part of human health, not an optional extra. The metabolic benefits of exercise are maintained by repeated use, and when training stops, some of those adaptations can gradually regress. Understanding triglycerides in athletes therefore helps reframe the lipid panel: low values often reflect metabolic fitness, while changing values may offer an early clue that the athlete’s training, recovery, diet, or broader metabolic context has changed.
References
[1] https://jamanetwork.com/journals/jama/fullarticle/193847
[2] https://pubmed.ncbi.nlm.nih.gov/3374323/
[3] https://pubmed.ncbi.nlm.nih.gov/8028501/
[4] https://pubmed.ncbi.nlm.nih.gov/36028221/
[5] https://pubmed.ncbi.nlm.nih.gov/18319352/
