Excerpts are created for Archive and categories, but not on the main blog page. The template for the blog page is 

<?php

/*

Template Name: blog

*/

?>
<?php get_header(); ?>

<div id="wrapper">

<div id="blog-content">

<?php /* Start the Loop */ ?>

<h2>Custom-diets blog</h2>
<?php while ( have_posts() ) : the_post(); ?>

<?php get_template_part( 'content', 'page' ); ?>
<?php endwhile; // end of the loop. ?>
<?php /* Display navigation to next/previous pages when applicable */ ?>

<?php if ( $wp_query->max_num_pages > 1 ) : ?>

<nav id="nav-below">

<div class="nav-previous"><?php next_posts_link( __( '<span class="meta-nav">&larr;</span> Older posts', 'ilisa' ) ); ?></div>

<div class="nav-next"><?php previous_posts_link( __( 'Newer posts <span class="meta-nav">&rarr;</span>', 'ilisa' ) ); ?></div>

</nav><!-- end #nav-below -->

<?php endif; ?>
</div>

<?php get_sidebar(); ?>
 
 

<!-- END #content -->

<?php get_footer(); ?>