About Terrence Merriman
Subsequent research, examining an even lower energy availability (i.e., 10 kcal·kg FFM·day−1) also reported significant decreases in LH production and LH pulse frequency . Initial investigations reported that a low energy availability (i.e., 13 kcal·kg FFM·day−1) significantly altered LH pulse frequency and amplitude . Low energy availability may reduce the body’s energy reserves, limiting its ability to support normal physiological function needed to maintain optimal health . Similarly, Clemesha and colleagues reported that only ~25% of the 50 products they tested claiming to be testosterone boosters had scientific data to support their claims. However, other investigators examining another phospholipid (i.e., phosphatidic acid) reported an increase in both strength and muscle thickness in young, healthy men .This is why high-protein diets show modest metabolic advantages. Your body works harder to process protein than carbs or fat. So, if you have more uncoupler proteins, you could have a higher metabolism, making more heat and still needing/burning through more food to make the necessary ATP. Cortisol breaks down potential stored energy (muscle and fat) and these molecules can be turned into glucose to support blood sugar during exercise and generate ATP to support the exercise. In order to do such, you need to break down proteins (mainly muscle) and fat to make new glucose. Both estrogen and testosterone are anabolic hormones that help preserve bone and muscle mass. We burn calories after we eat and this increased energy expenditure typically lasts at least 5 hours.
A decrease in daily energy expenditure simply means you burn fewer calories over the course of a day. The "metabolism" that most people are thinking of is Basal Metabolic Rate, the calories (amount of energy) expended while at rest, which is fundamental for understanding an individual’s energy requirements. However, successful long-term weight management requires attention to food quality, protein adequacy, metabolic health markers, and individual response rather than calorie numbers alone. Your gut bacteria may influence energy extraction from food, appetite regulation through gut-brain signaling, and inflammatory pathways affecting metabolic function. Resistance training is crucial for maintaining muscle mass and metabolic rate during weight loss. Rather than pursuing aggressive calorie deficits, more moderate approaches that preserve muscle mass and metabolic rate may be more sustainable.
Dietary pattern scores that were derived from each participant represented the sum of food intake variables weighted by the corresponding factor loading. The body mass index (BMI) was calculated as the weight divided by the height squared (kg/m2). Five commonly used cooking methods for protein-rich foods and the frequencies of eating outside and homemade food were also included. Malnutrition (e.g., protein restriction or a protein-energy deficiency) was suggested to impair Leydig’s cell function and affect T biosynthesis 26,27. Elevated serum ferritin (SF) predicts low total T levels in Chinese adults and young adolescent Taiwanese males . Several epidemiological studies demonstrated an inverse relationship between obesity and circulating total T concentrations 5,6,7,8.
T3, the active form of thyroid hormone, can decrease during calorie restriction, reducing basal metabolic rate by 10-15%. The amino acids from protein serve as building blocks for neurotransmitters, immune cells, enzymes, and countless other essential molecules. Carbohydrates have a moderate thermic effect of 5-10%, while fats have the lowest at 0-3%. Protein has the highest thermic effect at 20-30% of calories consumed. When you eat, your body must work to digest, absorb, and process nutrients. The first law of thermodynamics tells us that energy cannot be created or destroyed, only transformed.
Understanding that not all calories are equal doesn't mean calories don't matter. Some evidence suggests ultra-processed foods may be absorbed more rapidly than minimally processed whole foods with similar calorie content. Ultra-processed foods are designed to be highly palatable and easy to consume quickly, potentially leading to overconsumption before satiety signals register. While we've focused on macronutrients, micronutrient content also matters for metabolism. Chronic stress elevates cortisol, promoting fat storage around the abdomen. Sleep quality, stress levels, and meal timing can all influence calorie processing. Reasons include genetics, brown adipose tissue activity, previous dieting history, and gut microbiome composition.
Interestingly, Almstrup and colleagues reported that red clover flowers inhibit aromatase activity at low concentrations, but become estrogenic at higher concentrations, resulting in a U-shaped dose–response curve. Shufelt and colleagues reported that red wine consumption resulted in significantly higher FT concentrations and lower SHBG and E2 concentrations in women. Jeong and colleagues reported four compounds isolated from this plant, including diethyl ether extract, inflexin, ursolic acid, and ursolic acid 3-O-acetate that have significant aromatase inhibitory activity. The effect of various food groups, macronutrients, and micronutrients on testosterone circulation and its proposed mechanisms. While other reviews have previously discussed the effect of nutrition on testosterone status 13,14,15,16, most of these papers have examined the role of single nutrient (macro/micro) or food/food groups.
Other flavonoids such as catechins exist in high concentrations in cocoa , prune juice , and Açaí oil . There are numerous other plant extracts from collards, tomato leaves, tea, coffee, cocoa, kale, potato leaves that have been reported to have high aromatase inhibition activity . Sultan and colleagues reported that an extract from saw palmetto (Serenoa repens), a type of a palm tree, decreases in vitro 5α-reduction of androgens. To the best of our knowledge, this is the only study that has examined the anabolic effects of Garcina mangostana in humans. Balunas and colleagues reported that an extract from a tropical fruit called mangosteen had strong inhibitory capabilities of the aromatase enzyme. Red clover flower extract, often used to improve hair and skin texture 33,34, has also been reported to inhibit 5-α-reductase activity .
When it comes to losing weight, eating in a calorie deficit should always be your biggest priority, but food quality is important as well. Conceptualized and designed the study, revised the initial manuscript, and approved the final manuscript. In addition, the RRR is a method that relies on prior knowledge of biological relevance to select response variables.