The optimal timing for consuming carbohydrates and proteins during the day is a frequent topic of discussion among nutrition experts and the general public alike. While there's no single universal answer, the body's energy expenditure typically decreases during the night. However, dietary needs can vary significantly based on an individual's goals, such as following a hypocaloric diet or being an athlete. Experts generally recommend including all macronutrients—carbohydrates, proteins, and fats—in varying proportions at breakfast, lunch, and dinner to ensure a balanced intake. For instance, a pasta dish at lunch can be balanced with vegetables and a protein source like legumes or fish, while a main course at dinner can be accompanied by a side dish and a carbohydrate source such as bread or potatoes.
Generally, for non-athletes, many personal trainers and nutritionists still advise against consuming carbohydrates in the evening. This recommendation stems from metabolic considerations, specifically the link between carbohydrate intake and an increase in blood glucose levels, which can be a precursor to conditions like type 2 diabetes and hypertriglyceridemia, and can contribute to adipose tissue accumulation. The body's insulin metabolism is more efficient in the morning than in the evening, independently of pancreatic activity. Consuming more carbohydrates during the day, particularly for individuals with insulin resistance or diabetes, can help reduce post-meal insulin and glucose levels, thereby minimizing fat deposition.
The nocturnal period, following the evening meal, is characterized by the lowest caloric expenditure of the entire day. Unlike breakfast or lunch, which provide energy for daily activities, dinner does not need to support significant subsequent activities. Although the body requires nutrients, vitamins, and minerals, energy consumption is drastically lower at night. Consequently, carbohydrates, or glycides, should ideally be distributed during the hours preceding higher energy expenditure, mainly in the morning and at lunchtime.
The general guidelines discussed apply to most individuals, but exceptions exist, particularly for those on weight loss diets and athletes. Individuals aiming for weight loss, especially those following a low-carb diet or seeking to normalize hyperglycemia, must prioritize the universal principle of energy balance: consuming more calories than expended leads to weight gain, while a caloric deficit results in weight loss. This principle holds true regardless of the nutritional distribution between lunch and dinner. In such cases, carbohydrates should be consumed in moderation, primarily at breakfast and lunch, with reduced intake at dinner.
For athletes, the situation is different. Engaging in aerobic activities, which involve high glucose consumption and, consequently, significant muscle glycogen depletion, creates a glycogen debt. If dinner completely lacks carbohydrates, muscle recovery can be compromised, leading to a noticeable decrease in athletic performance. Therefore, athletes need to carefully consider their carbohydrate intake to support recovery and optimize performance. Proteins are also crucial for athletes, aiding in muscle recovery and growth.
Considering the body's fluctuating metabolic state and varying energy needs throughout the day, a nuanced approach to carbohydrate and protein distribution is essential. While general recommendations lean towards daytime carbohydrate consumption for most, individual circumstances like weight management goals and athletic demands necessitate personalized dietary strategies to optimize health, recovery, and performance. Balancing macronutrient intake across meals, with an emphasis on lighter, more digestible carbohydrates in the evening, can contribute to overall well-being and metabolic efficiency.