Avocado at Night: Adults with Prediabetes Have Lower Morning Triglycerides

Late-night snacking is a habit most people have, but its “composition” can influence how well the body handles the next meal in the morning (the so-called “second meal” effect). Avocado is a whole food with a low glycemic index, rich in monounsaturated fats and dietary fiber. The researchers wanted to see if eating a whole “avocado snack” at night would provide a metabolic advantage the next morning in people with prediabetes.

Background of the study

The question of whether late-night snacks are good or bad has long gone beyond “last meal after 6 p.m.” In modern nutrition science, the emphasis has shifted to timing and composition: it is known that food eaten the night before can change the metabolic response to the next meal — the so-called “second meal” effect. It has been described in experimental and clinical studies: a pre-snack or the characteristics of the previous meal can reduce glycemia and change the hormonal response to breakfast/lunch, with both macronutrients and the interval between meals being important. This makes a night snack a potential “tool for tuning” morning metabolism, especially in people with insulin resistance and prediabetes.

Against this background, avocado is an interesting candidate for a “smart” evening snack: it is a whole food with a low proportion of available carbohydrates, a high content of dietary fiber and a predominance of monounsaturated fatty acids (mainly oleic). Clinical reviews and chemical-analytical data confirm: a serving of avocado provides a combination of fiber + MUFA with a minimal glycemic load and moderate energy density - a combination that should theoretically have a beneficial effect on morning lipemia and the feeling of satiety.

Another important aspect is the concept of the “food matrix”: the physiological effect of a food is determined not only by the sum of proteins, fats, and carbohydrates, but also by how they are packaged and interact within the structure of the whole food. Previous studies have shown that snacks with the same calories and “macros” can produce different postprandial responses precisely because of differences in the matrix. Therefore, when evaluating a late-night snack, it is important to compare not only the “fat/fiber” per se, but also the whole avocado versus the “composite” equivalents.

Finally, the choice of triglycerides as a sensitive endpoint in people with prediabetes is not without merit: elevated TG and derived indices (e.g. TG/HDL) are associated with insulin resistance and residual atherosclerotic risk, and control of morning lipemia is considered a potential target for lifestyle modification. Hence the logic of the current RCT: to test whether an evening whole avocado snack can attenuate the morning rise in TG compared with isocaloric alternatives without worsening the glycemic profile.

How the study is structured

A randomized crossover study included 55 adults with prediabetes (mean age 44±14 years; BMI 28±6 kg/m²). Each participant received three energy-equal (280 kcal) evening snacks on different days at intervals and standardized consumption times (±1 hour), then observed a 12-hour overnight fast and underwent morning blood sampling before and within 3 hours after a standard breakfast (720 kcal). Primary endpoints were fasting and postprandial glucose/insulin; secondary endpoints were triglycerides and inflammatory markers. The protocol is registered at ClinicalTrials.gov (NCT05263011).

What exactly did they eat at night?

• Control: low fat, low fibre (isoenergetic 280 kcal).
• Avocado, whole food: "high fat + high fiber" from the avocado itself (280 kcal).
• Matrix Control: Same "high fat + high fiber" but made from individual ingredients (no whole avocado matrix), also 280 calories.

What happened?

No differences were found between the three night snack options for glucose, insulin, and inflammatory markers (p>0.05). Triglycerides tended to decrease with the fasting avocado snack (p=0.09), and most importantly, a significant snack×time interaction was found (p=0.02): 180 minutes after the standard breakfast, triglyceride concentrations were lower by ≈15 mg/dL compared to the control snack (effect −15.1±5.9 mg/dL; Cohen's d=0.70). This indicates a more favorable morning fat metabolism after the evening whole avocado.

What this might mean in practice

• The Whole Food Matters: Equal calories and macros don't guarantee the same response - the avocado's food matrix may have played a role.
• Triglycerides are a sensitive target in prediabetes: their morning reduction (even if short-term) is potentially beneficial against the background of insulin resistance.
• The “second meal” effect is real: the composition of an evening snack can “tune” the response to breakfast.

Important limitations

This is a short-term intervention with a standard breakfast and single measurements; the sample size is moderate (n=55). No significant changes in glycemia or inflammatory markers were shown; observation is limited to a few hours after breakfast - it is too early to draw conclusions about long-term risk, body weight and cardiovascular outcomes. The study was conducted in a single study group; the generalizability of the results to other populations needs to be tested. Communication materials about this RCT were distributed by industry organizations, which is important to consider when interpreting and setting expectations.

If you want to try it - with reservations

• Look at the calories: 280 kcal at night is not a little; take into account your daily balance and weight goal.
• Measure out your portion: half a medium avocado ≈ 120-160 kcal; the goal is not to “add” but to replace a less successful evening snack.
• Observe the “window”: finish your snack no later than 1-2 hours before bedtime, so as not to impair the quality of your night’s rest.
• Monitor your lipid profile and glycemia: with prediabetes, any food experiments are best combined with routine control tests. (This is general advice, not medical advice.)

Source: Preiss C, Marquis O, Edirisinghe I, Burton-Freeman BM. Using the Avocado as an Evening Snack to Investigate Whole Food Matrix and Macronutrient Composition on Morning Metabolic Indices in Adults With Prediabetes. Current Developments in Nutrition. 2025;9(7):107486. doi:10.1016/j.cdnut.2025.107486.