Beyond calories: Key to weight loss and fullness

A common feature of people trying to lose weight or wanting to prevent further weight gain is a lack of sufficient satiety and fullness, experiencing hunger, combined with a poorer mood, and expressed, for example, by frequent reaching for snacks.

Many studies so far have indicated a significant positive link between reaching for snacks and gaining excess body weight. (1, 2 ,3 ,4)

To put it bluntly, if someone has to eat snacks, there is probably something wrong with his/her diet.

Fortunately, in order to start experiencing greater food satisfaction and long-lasting satiety, so that a diet is not just a diet but a way of eating for life, all it takes is a slight manipulation of the macronutrients we consume.

There are three macronutrients: fats, carbohydrates and proteins, and it is these that we will address by examining which will most affect our satiety and which will least, or worse, reduce it.

Fats

Fat consumption can increase feelings of satiety through a number of different pathways, including effects on satiety hormones such as ghrelin (hunger hormone), cholecystokinin CCK (reducing appetite), GLP-1 (slowing gastric emptying) and PYY (regulating appetite).

These hormones play a key role in regulating how much we eat and the function of the entire digestive tract. (5)

Additionally some studies suggest the type of fat matter with monounsaturated fatty acids (MUFAs) eliciting weaker satiety response based on peptide YY (PYY) levels compared to polyunsaturated fatty acids (PUFAs) or saturated fatty acids (SFAs) meals.

Furthermore, the SFAs meal was associated with greater subjective feelings of fullness compared to MUFAs and PUFAs meals. (6)

Contrary to popular perception, however, fat may not be the best ingredient that leads to superior satiety, at least in the short term. We can read in a review by Koliaki et al. that “Fat, on the other hand, exhibits rather weak and insufficient ghrelin-suppressing capacity.” (7)

Fats vs. proteins

In study by Brennan et al. High-protein meals suppressed energy intake more effectively than high-fat meals, which was potentially mediated by responses of CCK and ghrelin. (8)

Similarly Batterham et al. suggested proteins have been shown to have a greater effect on satiety than fats. Protein intake led to an increase in satiety hormones like PYY and reduced energy intake compared to fats. (9)

Fats vs. carbohydrates

Study by Rolls et al. is among many that found: “High-fat preloads suppress lunch intake less than high-carbohydrate preloads, suggesting a relative insensitivity to the satiating effect of fat in obesity development and maintenance.” (10)

According to a comprehensive review by Kaviani and Cooper there is very inconsistent evidence on the impact of fats on hormonal and subjective measures of appetite and food intake pointing out that fat is not the most important element we would like to take care of for the sake of greater satiety, less snacking and consequently a lower probability of being overweight. (11)

Carbohydrates

Previous trials pointed out that carbohydrates can inhibit hunger faster than fats.

This would be consistent with the mechanisms by which carbohydrates act in this initial phase on at least one of the most important satiety hormones - ghrelin: “Carbohydrate appears to be the most effective macronutrient for ghrelin suppression, because of its rapid absorption and insulin-secreting effect.” (12)

Many other studies have confirmed the positive early impact of carbohydrates on satiety and food intake through various mechanisms, including hormonal responses of ghrelin, insulin, and other satiety-related hormones. (13, 14, 15, 16, 17)

However, as it turns out, and as I stressed earlier, this is the initial and short-term effect of carbohydrates on satiety. Within, for example, less than 2-3 hours, this effect can be the opposite and thus hunger levels back or even higher.

We can read: “More specifically, they observed only after CHO (carbohydrates) ingestion a marked rebound of acylated ghrelin to 37% above baseline levels, during the second 3 hours of the 6 hour post-ingestive period. (...)

No such overshoot was observed after protein or lipid ingestion, both of which suppressed acylated and total ghrelin levels until study completion. These observations suggest very different effects of high CHO meals in the early versus the later postabsorptive phase, indicating that ingested CHO might prompt an early hunger rebound.” (18)

For example Paula C Chandler-Laney et al. while comparing higher carbohydrate/lower fat with lower carbohydrate/higher fat breakfast meals found modest increases in meal carbohydrate content resulted in earlier rise and fall of postprandial glucose concentrations and an earlier return of appetite, thus increasing the probability of eating more and further weight gain. (19)

Proteins

As most studies show, proteins exert the most pronounced effect on satiety and hormonal responses compared to carbohydrates or fats. This is related to protein's effects on various hormones, including PYY, ghrelin, GLP-1, and CCK and more.

For example, Batterham et al. suggested high-protein intake increases peptide YY (PYY) release, leading to satiety and weight loss, whereas Koliaki et al. confirmed “Protein induces prolonged ghrelin suppression and is considered to be the most satiating macronutrient.” (20, 21)

Best macronutrients combination for satiety

Summarizing the above reports from the scientific world about which macronutrients are responsible for the highest and, importantly, long-lasting satiety, we can conclude that the most effective thing we can do is to maximize protein intake while reducing carbohydrates.

A number of clinical trials have also demonstrated this in practice.

In a study with type 2 diabetes (T2D) patients carbohydrate-reduced higher-protein diet (carbohydrate/protein/fat: 30/30/40 versus 50/17/33) reduced glucose excursions, improved beta-cell function, and increased subjective satiety by 18%. (22)

Similarly in a study by Ohlsson et al. a lower carbohydrate and higher fat and protein content provided greater satiety and attenuation of glucose and insulin. (23)

Low carbohydrate diets seem to be more effective in providing satiety than low fat diets as found in a randomized trial on 148 obese adults. (24)

Johnstone et al. in a study on obese men showed high-protein (30%), low-carbohydrate (4% carbohydrate) ketogenic diets reduce hunger and lower food intake significantly more than do high-protein (30%), medium-carbohydrate (35% carbohydrate) non ketogenic diets. (25)

Best food for satiety

Based on the known mechanisms of action of individual macronutrients on satiety and the diets that can especially contribute to it, it is worth mentioning specific products that will prove good, in particular, in providing long-term satiety and preventing snacking.

Among such, both nutrient-rich, protein-laden and low-carbohydrate, which we know promotes satiety, as well as well-studied would be eggs or meat.

Study by Keogh and Clifton found egg breakfast reduced more hunger than cereal based breakfast and returned later than after carbohydrate based breakfast consisting of cereal with milk and orange juice.

As a result: “Energy intake following the egg breakfast was significantly reduced compared with the cereal breakfast (4518 vs. 5283 kJ, p = 0.001).“ (26)

In another study, an egg diet compared to a bagel diet (both with a 1,000 kcal deficit) showed a 61% greater reduction in BMI and 65% greater weight loss over 8 weeks.

The authors concluded: “The inclusion of eggs in a weight management program may offer a nutritious supplement to enhance weight loss.” (27)

Leidy et al. compared egg- and beef-rich breakfast (35 grams protein) to cereal-based breakfast (13 grams protein) in a study on adolescent girls. Higher protein breakfast led to greater satiety and fullness.

Moreover, higher protein but not lower protein breakfast was associated with reduced evening snacking in these girls. (28)

Additionally, for those who like to add fruits or vegetables to their meals, fiber can also increase satiety, although to a lesser extent than protein. (29, 30, 31)

The bottom line

The key not only to maintaining our desired body weight but also to long-term satisfaction with food is adequate satiety of meals.

Based on the studies cited earlier, it can be concluded, although still against general recommendations, that we should focus on providing more high-quality protein, while not overdoing the carbohydrate content of the meal.

This is a reason why low-carbohydrate/ketogenic/carnivore diets are known to give satiety, so that the daily number of meals can be limited to 1-2 in a large number of cases.