The Lean Body Shortcut: Why More Men Are Turning to Intermittent Fasting
When you train regularly and eat well but still feel bloated while your body fat percentage stays stubbornly high, it can be frustrating. One increasingly popular approach is intermittent fasting. Even leaving a simple 12-hour gap between dinner and breakfast can support fat metabolism, digestion, and overall health. To better understand how intermittent fasting works, we speak with Italian physician Dr. Bruno Lucchino, who personally follows the fasting method.
At its most basic level, intermittent fasting can be as simple as leaving a 12-hour gap between dinner and breakfast. This time-restricted eating window gives the body a longer break from digestion, allowing metabolism and hormones to shift toward fat burning and recovery. Many people gradually extend the fasting period to 14 or even 16 hours, depending on their goals and lifestyle.
The benefits go beyond weight management. During fasting, insulin levels drop, helping the body access stored fat for energy. At the same time, growth hormone levels can rise, supporting fat burning while helping preserve muscle mass. Longer fasting windows may also activate autophagy, the body’s natural cellular recycling process that helps repair damaged cells and support metabolic health.
Intermittent fasting can be particularly effective in targeting visceral fat—the fat stored deep around internal organs that is strongly linked to metabolic diseases. Research suggests that fasting periods of 12–16 hours can accelerate fat burning and improve metabolic flexibility, teaching the body to switch efficiently between carbohydrates and stored fat as fuel.
“Intermittent fasting can be particularly effective in targeting visceral fat”
The most common way to practice intermittent fasting is through time-restricted eating, such as the popular 16:8 method, where food is consumed within an eight-hour window and fasting lasts for sixteen hours. Others begin more gradually with a 12:12 or 14:10 schedule. Another widely used approach is the 5:2 method, where normal eating continues five days per week while calorie intake is significantly reduced on two non-consecutive days—usually to around 500–600 calories. This approach offers many of the metabolic benefits of fasting while allowing greater flexibility in daily routines.
To better understand how intermittent fasting affects the body and how it can be applied safely, we spoke with Dr. Bruno Lucchino, a physician specialized in Rheumatology in Italy. In addition to his clinical work, he personally follows intermittent fasting methods and shares insights from both medical research and his own experience.
GWF: Can you briefly introduce yourself — what kind of doctor are you, and where are you based?
Hi my name is Bruno Lucchino, I’m a physician specialized in Rheumatology, working in a University Hospital in Milan, Italy.
During my medical studies, I started to get theoric notions about metabolism and nutrition, as part of normal medical education. In the same years I started to practice Crossfit, which soon became a passion and I have been practicing since 13 years now. This allowed to put in practice on myself and on my performance what I was studying.
GWF: When did you first start practicing intermittent fasting, and what motivated you to try it personally?
At the beginning, I was on IF (Intermittent Fasting) just for some periods, but by time it became part of my lifestyle, and currently I basically follow it on a daily basis. Indeed, reducing the window of time dedicated to meals has the advantage of saving time which can be spent in work or training.
Moreover, IF is really dynamic speaking in practical terms and can be easily adapted to individual goals.
“If I need to get a bit shredded I add one or two weeks on 5:2, which give immediate results”
GWF: Do you follow a consistent fasting method year-round, or do you adjust your approach depending on your goals?
Generally speaking there are two methods of IF:
- Daily Method, mostly 16:8, which consists in 16 hours of fasting followed by a feeding window of 8 hours. This is done on a daily basis, and it offers you several metabolic and body composition benefits. It is sustainable medium to long term. The duration of the fasting: feeding windows can also be modified in base of individual goal, for example 14:10 or even 12:12 (for example longer feeding windows may be more indicated during bulking periods).
- Weekly Method 5:2, in which 2 days per week are restricted in calories (max 500-600 kcal) while other days are normocaloric. This can be extremized up to the so called eat-stop-eat in which the 2 days are full 24 hours of complete fasting, which is brutal but is a huge boost for lipolisys and autophagy.
For my personal experience I usually follow a 14:10 daily as standard, when I want a good compromise between sport performance and body composition, modifying the windows if I want to bulk or cut. If I need to get a bit shredded I add one or two weeks on 5:2, which give immediate results.
GWF: Have you noticed specific changes in your body composition, energy levels, or focus since adopting intermittent fasting?
In general, mental focus and energy levels are pretty improved by 16:8 IF, because your body gets used to shift more easily from carb to fat metabolism. Insulin levels become more stable, lowering brain fog and that easing that drowsiness feeling in the afternoon. The same metabolic mechanisms are responsible for an improved body composition, with lower body fat and higher muscle mass, compared to a diet with same calories but not including fasting.
GWF: When you’re aiming to get truly lean, you said you switch to the 5:2 method — why does that strategy work so well for you?
Introducing 2 days of fasting is a huge metabolic boost, because it lowers insulin levels while spikes up lypolitic hormones, including GH, glucagone, cathecolamines, consuming the body stored fat as main source of energy. Moreover it creates an absolute caloric deficit, because it requires a maxium caloric intake which has to be respected in the fasting days. If you consider for example a 3000 kcal per day diet, at the end of the week you ll get a 5000 kcal deficit, which is really difficult to compensate on the other days by overeating, because those are already normocaloric.
GWF: From a medical perspective, what happens in the body differently with 5:2 compared to 16:8?
The two approaches share a core of similar mechanisms but differ in term of intensity of the metabolic change.
In general fasting lowers insulin levels and increases insuline sensitivity, increases lypolitic hormons during fasting (GH, glucagone, noradrenaline), and shifts metabolism through fat oxidations and ketosys.
In daily fasting, you get a moderate metabolic shift which results in a progressive but slower reduction of body fat with a general preservation of muscle mass. Indeed, an importan mediator of GH activity which is IGF1 is not lowerd by short time of fasting, and this allows to preserve muscle mass, resulting in mostly a body recomposition.
On the other way weekly fast gives you a brutal metabolic boost, with a higher spikes of lypolitic hormones and ketosis, resulting in a way higher fat oxidation but at the same time a muscle mass loss. For this reason is should be limited in term of frequency, to avoid muscle catabolism. Anyway some of metabolic adaptations, including ketosis and boost of autophagy get a significant increase only with this type of fasting, and are actually considered the main responsibles of the anti-inflammatory effect of the IF, allowing several potential health benefits.
GWF: Do you think intermittent fasting is suitable for everyone, or are there people who should avoid it?
In general some medical conditions, mostly diabetes under hypoglicemising drugs, such as insulin, is an absolute contraindication, for the risk of hypoglycemia. The same applies in other endocrin pathologies, such as thyroid disfunction. People with behavioural eating disorders should be dissuaded, mostly for the psychological consequence of a radical change in diet. I’d suggest also caution in situations like intense exercise or competitions, in which you probably need a more stable metabolic state.
GWF: Many people struggle with hunger at the beginning — what practical advice would you give to someone starting 16:8?
It is pretty common, but it takes only 10-14 days for the morning hunger to subside, because huger hormones such as ghrelin, get progressively regulated. Some tips can help: staying hydrated, taking coffee or tea in the morning for the caffeine’s anti-hunger effect. And the choice of food: slow release complex carbs and a protein rich meal as last meal of the feeding window can help to not suffer the fasting window.
GWF: How important is food quality during the eating window? Can someone fast and still eat poorly?
That’s indeed the biggest cause of failure of IF. People thinks that fast can compensate a poor diet, which is in part true, but has the effect of a lower stability in energy levels. If you eat junk and high simple sugar food during the feeding, the effect on insulin levels will get larger obscillations, resulting in less stable energy levels and making IF not sustainable over time. Good choice of energy are dense foods like proteins, healthy fats, complex carbs and fibers are the base for getting all the benefits from IF.
GWF: As someone in the medical field, what are common misconceptions about intermittent fasting?
For sure the main fear is the lack of energy by skipping a normal schedule meal, with the sensation of fainting being the first thing that people bring up when talking about IF. We know anyway that the origin of this sensation is almost completely psychological because our body is biologically designed to stay resistant through hours of fasting, unless you have a medical condition. The second is the fear of losing muscle, the spooky “catabolism” of the gymbros, which can be easily avoided just adapting IF to your characteristics.
GWF: Finally, what’s your number one tip for men who want to reduce body fat while maintaining muscle?
I think that patience and resilience are the most important advices to give. Change needs time and signs of improvement needs even more time. Trying a new approach with the main aim of feeling better versus than losing weight can be the key to improve both how you look and how you live.
